->"''You don't like the way I phrased an answer. What kind of evidence is that?''"
-->-- '''The guy who did it''', ''Series/{{Monk}}'', "Mr. Monk Fights City Hall"

The classic whodunit challenges the viewer to solve the crime along with the detective. Since the viewer isn't a professional, the crime has to be set up so that the solution doesn't rely on skills only a professional criminologist would have. These mysteries often work by reducing the crime to a logic puzzle: you solve the mystery by finding the fact that doesn't fit.

The problem with this is the "solution" at the back of the book doesn't give the perp a chance to offer a perfectly reasonable explanation.

Real crimes aren't logic puzzles and mere factual inconsistencies aren't a substitute for hard evidence. Poking holes in a suspect's story might push a jury towards the edge, but it's not going to convince them by itself. You might be able to PullTheThread, but on its own, proving that the suspect lied about something doesn't prove he committed the crime (especially if he has a BigSecret). At best, this kind of logic game can be used during PerpSweating to get a confession. At worst, [[Literature/EncyclopediaBrown Detective Brown]] will arrest the perp immediately, but Franchise/PerryMason wouldn't even break a sweat getting an acquittal from that.

More realistic examples focus on the investigative side, where the contradiction satisfies the significantly lower standard of proof required to ''arrest'' someone and investigate them further, rather than the much higher standard to ''convict'' them, or on non-legal contexts where the solution is just about swaying people's opinions rather than meeting any rigorous standard of proof. Some stories {{handwave}} this issue by having the contradiction leads to further investigation and the discovery of more concrete evidence. In stories involving teenage perpetrators, the crimes are often rather minor and the solution has them immediately confess when the contradiction is pointed out; this is somewhat less plausible against adult suspects, but even in RealLife, plenty of people don't know their rights or make mistakes when pressed.

Note that in modern legal systems, it is far more realistic to have this trope derail a ''prosecution'', both because the defense only needs to introduce the possibility of reasonable doubt (which a contradiction in a witness statement often accomplishes), and because the prosecution has the burden of having to prove their case. A contradiction in the defense's alibi doesn't necessarily prove them guilty if the prosecution otherwise failed to make its case; but for the prosecution, even an entirely innocent mistake in a key witness statement can call the credibility of the entire statement into question and cause the case to collapse.

See also ConvictionByCounterfactualClue, which is when the "flaw" found to prove the suspect's guilt is simply erroneous. This overlaps with HyperAwareness—sometimes it's just hyper-awareness taken too far, to the point of noticing details that logically shouldn't even be noteworthy. Can lead to a minor InferredHolocaust, if logic dictates that the supposedly happy ending will lead to either a guilty character escaping or an innocent one being convicted. These types of inferences often run afoul of HanlonsRazor, blaming every flaw or contradiction on lies and conspiracy rather than, say, faulty memory or panic.

Compare INeverSaidItWasPoison, where the suspect demonstrates knowledge of a detail or two they shouldn't.

This gets particularly JustForFun/{{egregious}} when the story contains perfectly good alternative clues, but the flimsy one was chosen as ''The'' Clue.


[[folder:Encyclopedia Brown]]
%% The reason for an entire section on Literature/EncyclopediaBrown is he's the TropeCodifier with the largest number of examples!
* This has happened so often in Encyclopedia Brown shorts that [[Administrivia/RenamedTropes the former Trope Name]] was "Bugs Meany Is Gonna Walk".
* A "witness" trying to frame a boy for the theft of a pocket knife claims the boy took the knife with his right hand, and put it in his pocket while running away. He is found innocent because he has a cast on his left hand and the knife was found in his left pants pocket (planted there by the "witness") and (according to the answers section at least) it's impossible to put a pocket knife in your left pants pocket with your right hand while running. Leaving aside that Encyclopedia was assuming an impossibility out of a difficult and highly improbable physical stunt, the mere likelihood of him putting the knife in his left pocket after he'd stopped running never occurred to him. Of course, since the inconsistency here is being used on the defendant's behalf to ''create'' reasonable doubt, it's more valid than most of the other examples on this page.
* The perp claims to have been out of town during the crime, but knows details about some contemporaneous local event (because, clearly, he never talks to anyone about local events or reads newspapers).
* The perp claims to have seen something by moonlight on a night when there was no moon. It's entirely possible that the perp saw the incident by another ambient source of light and simply assumed it was moonlight. Interestingly, UsefulNotes/AbrahamLincoln got an acquittal in a case in [[http://en.wikipedia.org/wiki/William_%22Duff%22_Armstrong exactly this manner]], though in his case it was used to show that, without moonlight, it would have been impossible to see something 150 ft away at night in 1858.
* A boy blows his fake alibi by tracing a shirt pocket on the wrong side of his chest. This is perfectly understandable, since everyone is accustomed to seeing images of themselves in the mirror, where left and right are flipped.
* A man accused of committing a robbery is being interrogated in the crime scene and claims he has never been there before. Shortly afterward, he says, "When you brought me ''back'' here, did I resist?" to the police officer. Since he couldn't be brought ''back'' if he had never been there before, the man is guilty. First of all, the term "back" doesn't have to mean "return." It can simply indicate distance or location, shown in common phrases such as, "He's from back east." You can also say you're taking someone "back" somewhere if ''you've'' already been there. The all-too-common example would be asking a stranger, "Want to go back to my place?"
* A perp claims to have been on the bottom floor of a building when the crime was committed, yet when he went to the elevator, he pressed the "up button." Encyclopedia deduces that the perp was probably not on the very bottom floor, because the perp wouldn't have had to distinguish the button as the "up button" because there wouldn't have been a "down button." Of course, an "up button" is always an "up button" whether or not there's a "down button" along with it. The actual name for them is "call button", but it's rarely used outside of technical and legal documentation. Besides, plenty of call buttons still have the appropriate arrow on them even when they're on the top and bottom floors.
* The perp tells someone he's hidden a $2 bill between an odd and even page of a book that are normally on opposite sides of a leaf if the book is read left to right. It might be possible that the book had a typo, breaks the tradition, had its pages printed out of order, or the perp simply misremembered the book pages.
* A stolen rare coin is found inside Bugs Meany's hot dog. How did Encyclopedia know where to find it? Because he saw Bugs spread mustard ''on top'' of the sauerkraut, and "[[SeriousBusiness no one who]] [[NoTrueScotsman likes hot dogs]] [[InsaneTrollLogic does that]]." Admittedly, it is a pretty messy way to go about things (similar to trying to spread peanut butter on top of jelly), but c'mon. Interestingly, the story effectively admits Bugs ''would'' have walked if he'd been willing to finish his hot dog, and presumably swallow the coin in the process. Also a case of TechnologyMarchesOn, as a modern reader would expect the mustard to come out of a squeeze bottle and be easier to have on top than the sauerkraut. Plus, who's to say Bugs hadn't just ''overlooked'' the mustard jar, or that someone else was hogging it, when he first started applying his hot dog toppings?
* The perp buys time to rob his victim's house by asking the victim to add four tubes of toothpaste to his supermarket order of seven items. This required the victim to check out in a regular shopping lane instead of the 10-items-or-less express lane, which otherwise would have allowed him to return in time to see his house being robbed. Brown figures it out because the perp was the last of the victim's friends to ask for items, and his order was too plainly designed to surpass the ExpressLaneLimit. Of course, the fact that the perp counted on both the victim and grocery staff to obey the letter of the express lane rules and for the express lane line to be open and available at the same time he was at the store pretty much means he deserved to get caught.
** Even Donald Sobol (the author of Encyclopedia Brown) [[EveryoneHasStandards seemed to realize that this one was flimsy]]; Mrs. Brown specifically mentions that the store is notorious for demanding ''exactly'' ten items for the express lane. That doesn't quite fix the problems (again, the lane might not have been open in the first place), but points for trying.
* Bugs Meany holds a raffle drawing at a fair for a baseball glove and has one of his friends [[DoesThisRemindYouOfAnything reach around for another associate's balls]] in the big container of ping-pong balls. Encyclopedia discovers he was cheating by noticing that Bugs drank a canned soda when he was carrying around a thermos, thus meaning he put the ball in the freezer, then took it to the fairgrounds in the thermos so the associate would just have to feel around for a frozen ball. It's entirely possible that Bugs simply didn't want whatever was in his thermos at that particular moment or was ''saving'' it for later. Or that he'd already emptied his thermos, and found himself wanting another drink.
* A carnival tent gets upended, and the take is stolen in the confusion. When Encyclopedia studies the injuries of the performers, he suspects the magician; the reason? He's wearing a short-sleeved outfit, and "all magicians wear long sleeves to hide things in." This example is also listed under ConvictionByCounterfactualClue.
* Two precious ivory bookends belonging to a former circus owner are stolen when two of the man's friends are visiting. Encyclopedia and his father find strange handprints in the beach near the circus owner's house, and so suspicion falls on one of the visitors, a crippled acrobat, because the only way he could have walked was on his hands. Encyclopedia, however, insists that the thief is in fact the other visitor, a former bareback rider, because she said her leather gloves were missing, and "no one brings leather gloves to a seaside town in the summer." (Because she couldn't possibly have brought the gloves for a legitimate reason like playing golf, as driving gloves, or even riding a horse. And she ''certainly'' couldn't have packed them by accident. Or maybe she just really liked the gloves and bring them everywhere.)
* A perp who's trying to frame Encyclopedia for claiming ownership of the town clock and charging people to use it to set their watches is "proved" as a liar because he used his left hand to set his own watch, because of the "fact" that when you set your watch with your left hand, you're holding it upside down. (Because it's impossible that a person could simply be more comfortable using their left hand, and compensate for it when setting their watch, or that one could buy left-handed watches specifically to avoid this problem, and ignoring that watch faces are quite easy to read upside down.)
* A perp is accused of stealing something that belonged to Encyclopedia's client, and riding away on her bicycle. She claims that she hasn't ridden her bike all summer, before she takes it out of storage and starts showing off on it. Encyclopedia declares that she's lying, because if she hadn't ridden the bicycle like she claimed, the tires would have gone flat. (Because it's impossible that the girl or her parents could have kept the tires inflated in case she ever decided she wanted to go for a bike ride.)
* A man tries to claim insurance money on a painting he's reported stolen. His story goes that while shaving after a shower, he saw reflected in the mirror a man stalking away with the painting. Encyclopedia explains that the claim is a fraud because a mirror would be foggy after a shower and so the man wouldn't have been able to see anything. (Never mind that it only takes a second to wipe away condensation, something people often do when they ''need to shave''. Or cold showers, or how movement and shapes are still discernible through a foggy mirror. Or how some people use a fan or leave the bathroom door open specifically so that the mirror doesn't fog up in the first place. And finally, as ScienceMarchesOn, fog-free mirrors now exist.)
* A sailor wins a painting contest open only to amateurs. He is called out as a professional painter pretending to be a sailor because he failed to do the research on nautical terminology: he used terms like "left" or "right" when describing a boat he was painting rather than the nautical terms like "port" or "starboard", as well as the redundant phrase "knots per hour"[[note]] A knot is a unit of speed referring to approx. 1 nautical mile per hour. Technically, this would be acceleration[[/note]], mistakes that no one remotely familiar with sailing would have made regardless of their expertise level. However, while "he's a professional painter trying to pass as an amateur" is the most likely explanation for the masquerade and was probably sufficient grounds on its face to get him disqualified, he might have had other reasons for the pretense and it's not ironclad evidence he's an actual professional.
* Still another case hinged on the detective's belief that a real resident of San Francisco would never ever refer to the city as "Frisco." While it's true that residents of the city traditionally hate that nickname, it's not exactly an enforced law, at least not since [[http://en.wikipedia.org/wiki/Emperor_Norton Emperor Norton]] died.
* A case had a kid that finished last in a race correctly identify a song being played at a theater along the race route as "The Eyes of Texas," rather than (the presumably more identifiable to a kid in Idaho) "I've Been Working on the Railroad," "proving" that he stopped in to ensure that he would finish last. Because he couldn't simply have been a football fan who had seen the Longhorns play. This compounded by the fact that the [[ConvictionByCounterfactualClue two songs aren't even the same]]—"I've Been Working on the Railroad" has more lines, to a different tune.
* A blind man is the only witness to a crime; a perp fleeing the scene with a bag of cash crashed into him, and it is thought that the man might have felt his face well enough to identify him if he felt it again. Turns out the blind man is not blind, and was in on it the whole time: he swapped bags with the thief when they collided. How does Encyclopedia prove this? When he visited the man in his hotel room, the lights were on and there was a newspaper on the table despite the man claiming he hadn't had visitors in "a long time". Because no hotel in the world offers complementary newspapers that they put in your room. And they ''never'' have the lights on when you arrive. And a blind man would totally notice if they were on, and turn them off. This is a lesser example, however. Once Brown figures out what happened getting a doctor to confirm that the guy can see shouldn't be too hard. Overlaps with ConvictionByCounterfactualClue since most blind people aren't completely blind and it is entirely possible for one to leave the lights on and read a newspaper.
* Bugs steals an antique teacup. When Encyclopedia confronts him about it, Bugs claims that that it was a prized cup from the owner of a Chinese restaurant that has since gone out of business. Encyclopedia deduces that he's lying by noticing that the cup has a handle, which Chinese teacups do not have. (Because it's impossible for a Chinese guy to like American mugs, and of course, with globalisation Chinese teacups with handles do exist now.)
* One story had a girl having one of her sneakers stolen from her before a sneaker contest was held. The thief was identified because she said to another person that the girl had the sneaker stolen from her "while clipping her toenails", even though all the girl said was that she was "clipping her nails". And [[INeverSaidItWasPoison only the thief would know that she had been clipping her toenails and not her fingernails]] (even though if someone said she had her sneaker stolen while clipping her nails before a contest involving feet, most would immediately assume the nails WERE toenails, not fingernails.) There's no reason to take your shoes off to clip your fingernails, and it's a safe bet a person would notice someone stealing shoes that ''they were wearing at the time'', making it even less of a stretch to assume that toenails were meant.
* Encyclopedia's dad described a case to him after the fact that involved a professional tennis instructor who reported that a set of ivory screens had been stolen that morning. He saw the thief's face; it could be either of two identical twins—one who worked as a cashier and one who played tennis. Encyclopedia figures out that the victim was just lying so he could get insurance money for the screens, because the crook was wearing a T-shirt, and if the tennis player had been the culprit, one arm would be more developed, while equal arms would incriminate the cashier. This assumes that the cashier had the presence of mind to make such an astute observation, and also assumes the [[ConvictionByCounterfactualClue untrue "fact"]] that all tennis players have asymmetrical arms.
* In one story, a man claimed an item of his had been stolen during a thunderstorm. The house was dark because the power was out. He was awoken by a thunderclap, then saw the burglar ''in the lightning flash that followed''. E Brown knew that the man was lying (he had actually stolen his own property for the insurance money, then made up the story), since in real life, thunder follows lightning, not the other way around. Of course, it's inconceivable that there would be ''more than one lightning flash'' during the course of a thunderstorm.
* A contest is held in which contestants complete a quiz for 3 secret prizes for 1st, 2nd and 3rd place. The first place winner receives the best prize: a watch, which he discovers has been broken. The theory of the crime is one of the contestants secretly examined the prizes and played with the watch and broke it. The culprit turns out to be the 2nd place girl that purposely missed a question she should have gotten right: "Name a word that has three double-letters." The girl referred to herself as a "bookkeeper". This doesn't account for the possibility that the word simply slipped her mind at that exact moment. Or perhaps she can't spell it—thinks it only has one k, for example, or thinks it's two words. Or perhaps she hyphenates the word, as "book-keeper" (a valid, if rather old, spelling), splitting one of the double letters.
* One case was solved because the culprit claimed their wobbly table was knocked and various possessions spilled on the floor. EB points out that the table was three-legged, and that such tables can't tilt. Three-legged tables won't be wobbly even if the legs are different lengths. However, if the table was on a slant to begin with, jostling it might very well knock it over, or at least knock the items off.
* At least one time the series used this trope absolutely correctly. Bugs claims to have been kidnapped at Encyclopedia's behest (how a 5th-grader was able to hire and control adult {{Mooks}} is never discussed). He describes being imprisoned in a small room, and attempts to escape by removing the pins from the door hinges, but they are on the other side of the door. Then he tries to wait to the side of the door and jump his kidnappers when they come in, but the door opens into his face, foiling the attack. Standard house doors ''cannot'' open away from their hinges, only toward them.
* Encyclopedia Brown liked solutions where the answer hinged on an American city having the same name as a foreign place that was generally more famous, for example Paris, Texas. This isn't usually conviction by contradiction, but became a case of it in the answer to one puzzle involving an American city called Palestine, where Encyclopedia declared that it ''had'' to be the American city because "nobody calls the real one Palestine anymore." Apparently in Encyclopedia Brown's world, Palestinians don't exist. [[note]]Current political controversies notwithstanding, prior to the 1967 War the non-existence of Palestine was indeed generally considered a non-controversial matter.[[/note]]
* A boy gets injured in the foot by an unknown suspect. Another boy is asked to bring a spare shoe for the injured party. Brown deduces the other boy is the perp because he brought the right shoe for the injured foot without asking beforehand which shoe to bring. While common sense might suggest to the boy to think about which foot would need the shoe, he still had a 1 in 2 chance of getting the right shoe if it didn't occur to him right at that moment to ask and, although the wrong shoe might not fit comfortably, it could still fit his foot if the size allows for enough space. Encyclopedia does point out, however, that if the boy didn't know which shoe to bring, he would likely have brought back ''both'' shoes. The boy brought back ''only'' the one, however, which made Encyclopedia suspicious.
* A local con man claims to have bred chickens that can lay square eggs. He comes up with a lame {{handwave}} as to why he simply can't show them, and claims instead that he'll stage a publicity stunt by having the skydiver standing with him jump holding one in a box only to have it still intact afterwards but needs money for promotion. Encyclopedia calls him out because the skydiver is wearing only one parachute, and all jump with two in case one fails...because there's no chance that someone might wear something different to a publicity event than during actual skydiving. Granted the con man does describe his accomplice as dressed "ready to jump", but considering the whole absurdity of the situation (the convenient excuse as to why he can't just show the eggs, the fact that a square probably would be crushed if held by a skydiver anyway, why such a stunt would even be necessary to promote square eggs, and of course, what the hell besides novelty value is the benefit of square eggs anyway?) it seems kind of silly that Encyclopedia quibbles over such a minor technicality. The "Solution" page at the end of the book even admits that had Wiggins not embellished his con by bringing his friend along, Encyclopedia would have had nothing to use against him and [[TheBadGuyWins he could've successfully screwed the kids out of their money]].
* One story's suspect gives the alibi that she was in the shower at the time of the crime. During the "interrogation", she starts filing her fingernails, which Encyclopedia claims is proof of her guilt, saying that you never file wet nails because they're too brittle and will break rather than filing down evenly. The idea that the girl might have ''dried off'' after her shower apparently doesn't enter into his head.
** The idea she dried off is the mostly likely, but there's also the possibility she simply didn't know this fact. People sometimes do things they aren't supposed to do in regards to hygiene and/or beauty/grooming treatments due to not being exposed to helpful information or being feed bad information. Or being interrogated caused her to be nervous, filing her nails is a comforting mechanism, and even knowing it might temporarily ruin her nails, she ended up doing it anyways. Guilty or not, people under stress sometimes instinctively do things they'd know better than to do in normal circumstances.

* In the 1960s, Franchise/CharlieChan played with this trope to sell Volkswagens. In a TV ad, Charlie and company are gathered around the hospital bed of the perp he just fingered, and he explains how the seemingly obvious alibi—the man has his left leg and right arm in casts, therefore he could not have driven the stolen car—is no good after all. ''This'' Volkswagen has a [[UnintentionalPeriodPiece new-fangled]] "automatic stick-shift transmission", so there was no need to work the clutch and shifter.
-->'''Charlie:''' In conclusion, only thing evil man like Motley really need was far better alibi.

[[folder:Anime and Manga]]
* Inverted in ''Itsuwaribito''. The protagonists find out that a miracle religion is a front for a money scam. Both the founder and the first pupil claim that they are innocent and the other was manipulating him to get money. The protagonist asks both of them privately what happened. He first asks the pupil about what the founder did with the money, and the pupil answers that the founder never let anyone else close to it. Then the protagonist asks the founder how he didn't notice the money next to boxes of equipment, and the founder answers that he didn't notice the boxes of money. The protagonist finds that the founder is innocent because the founder incorrectly stated that the money was put into boxes when it was actually placed inside bags ''next'' to boxes. If the pupil was telling the truth, then the founder would have known that the money was put inside bags.

[[folder:Comic Books]]
* The Swedish edition of ''ComicStrip/ThePhantom'' had a few pages of reader-submitted letters and material for a long time; one mainstay was various whodunnits, of course concocted by one of the readers. While some were well-written, far too many that hinged on the culprit making any kind of factual fallacy (such as stating that Canada's capital is Toronto) which immediately had them busted. The one that set off the trend was admittedly fairly good; someone disguised as a Muslim imam, who orders a ham sandwich...
** One whodunnit was a murder taking place in Germany, and one suspect claimed to have been in the woods picking berries at the time, while the other said he had been at the movies seeing a Bond movie, and remarked on Bond's funny German accent. While the readers were supposed to suspect the latter (Bond is German?), certain little-known cultural traits were at work—movies are always dubbed over with German speech in Germany, whereas picking berries in wooded areas you don't own counts as theft and/or trespassing, in contrast to Swedish law which allows it. Although one has to wonder why a German person would remark on an accent being German. (If he thought it was a ''funny kind'' of German accent, that still wouldn't be the likely way of putting it.)
* One early ''Comicbook/{{Supergirl}}'' comic featured a woman impersonating a man claiming to be Supergirl's husband-that-she-forgot-she-had, in order to make her (the woman's) boyfriend give up his crush on Supergirl. Supergirl saw through this at the beginning, because the woman put "his" arms around Supergirl's neck when "he" kissed her rather than around her waist, which is apparently something ''only'' girls do. [[FridgeLogic Though she should be able to literally see through the disguise, being]] Comicbook/{{Supergirl}}.
* The first storyline in which Superman and Batman learned each other's secret identities (via ContrivedCoincidence) featured Batman concluding that someone was lying about being an electrical engineer because he wasn't wearing rubber-soled shoes. ''On a holiday cruise.'' While a) Superman had X-ray-spotted a gun in the suspect's pocket and b) the guy did claim to have a job to do in a few minutes on the ship's generators, it's still rather jarring that "[[InformedAbility The World's Greatest Detective]]" apparently concluded that no-one can own more than one set of shoes.
** If the above description is correct, there's another problem: an ''electrician'' is someone who works hands-on in electrical systems installation, maintenance, troubleshooting and repair, while an ''electrical engineer'' is usually someone who designs such systems but does not physically work on them.
* ''Franchise/ArchieComics''
** Inverted in one story. When Betty is framed for academic plagiarism, Archie investigates the evidence against her and points out the flaws in it that prove her innocence. He then offers actual physical evidence that proves that she was framed by a jealous rival.
** Inverted ''again'' in another story where Archie accidentally spills paint remover on an 1870 Frederick Church painting that Mr. Lodge buys from an art dealer. Mr. Lodge is predictably upset, but then Archie wipes away more paint and finds the signature "Picasso". Mr. Lodge is suddenly thrilled, thinking that he's actually discovered a long-lost painting by Creator/PabloPicasso, but then his butler Smithers reminds him that Picasso was born after 1870, the date when Church supposedly painted his picture. When it dawns on Mr. Lodge that Church couldn't have painted over Picasso's original painting if Picasso wasn't even ''born'' yet, he realizes that he's being conned. Mr. Lodge then takes back his check from the crooked art dealer, and gets Smithers to help him literally throw the dealer out of the house.
** Yet another story had Archie and Jughead housesitting for Mr. Lodge and Veronica while they went on a family trip. A crooked art dealer and one of Mr. Lodge's security guards use the opportunity to steal Mr. Lodge's collection of priceless paintings and replace them with forgeries, while trashing the Lodge house to make it look like Archie and Jughead threw a WildTeenParty and distract Mr. Lodge. When he comes home, Mr. Lodge falls for it and is furious with Archie and Jughead, but then Archie realizes that the paintings weren't at all damaged by the "party". He convinces Mr. Lodge that they were hung after the wrecking was done, and proves that they're fakes. Archie and Jughead then direct the police to the art gallery, where they find Mr. Lodge's real paintings. Archie explains that the crooked art dealer couldn't bear to damage his expert forgeries and ended up tipping Archie off to the fact that they were fakes, which makes this a case of HoistByHisOwnPetard.
* Regularly parodied in Comicbook/{{Viz}} magazine's strip ''Spot the Clue'', supposedly written by a different guest celebrity every month.
** When Tim Westwood "wrote" the strip, the murderer gave himself away by referring to an album that hadn't been released at the time the strip was set.
** When David Bellamy "wrote" the strip, the murderer revealed himself by giving a plant's botanical name in capital letters in his speech bubble.
** When Hugh Scully "wrote" the strip, the thief claimed she had been cleaning an Edwardian bureau at the time of the theft, when the style of carving on the bureau clearly showed it be be from another period.
** When Albert Camus "wrote" the strip, the murderer's lie was to say he enjoyed life, when in fact the inevitability of death renders everything we do meaningless and absurd.
** When Alan Sugar "wrote" the strip, the murderer claimed to have sent a message on an Amstrad eMailer, forgetting that Amstrad eMailers are shit and never do what you want them to do.
* Trixie Belden had several comic book stories. One involved a female suspect hiding out as a guy. The crook forgot that female shirts tend to button on the opposite side.
* The ''ComicBook/BruceWayneFugitive'' arc toyed with this; every time one of the bat-family found some piece of evidence indicating Bruce had been framed for Vesper's murder, someone would pipe up with the obvious: Bruce was more than capable of forging/planting that very same evidence to make them ''think'' he'd been framed so no amount of forensic evidence would ever clear him in their eyes. Ultimately, they decide to have faith in his innocence based on their personal experiences with him and not solid evidence of it.

* Played with in ''{{Film/Dogma}}'' – Loki argues to Bartleby that a couple is adulterous because "No married man kisses his wife like that." Bartleby retorts that it's a good thing Loki's never had to serve on a jury. So Loki asks the couple. HilarityEnsues.
* In ''Film/HarryPotterAndThePrisonerOfAzkaban'' (''not'' in [[Literature/HarryPotterAndThePrisonerOfAzkaban the book]] where it took a ''lot'' of explanations from all parties involved and pursuing every doubt before Harry believed the truth) the person who betrayed Potters was proven "guilty" because [[spoiler: he pretended to be a rat for the last 12 years]]. Curiously enough, the book offers a plausible explanation why he would do this if he's innocent:[[spoiler: he claimed he was scared for his life, since a person thought to be a Death Eater tried to kill him, and others might try this as well]]. While this ''was'' why he was considered a suspect in the first place it was other evidence that convinced Harry of his guilt.
* In ''Film/InglouriousBasterds'', Archie Hicox, an Englishman pretending to be a German, is doing a good job of staying undercover amongst Germans... until, rather suddenly, the Gestapo officer he's been talking with says that he's given himself away. That's because Hicox, when ordering a round of drinks, uses the British hand gesture for "three" (index, middle, and ring fingers raised) instead of the German one (thumb, index, and middle fingers raised). German audiences naturally pick up on it more easily (and it's explained later for other audiences), aided as well by the fact that Hellstrom visibly reacts to it. It helps that Hellstrom was already suspicious of Hicox, such as [[OohMeAccentsSlipping his difficulty at a German accent]], his hostility to Hellstrom's presence and insisting he leave, and that the Basterds have pulled the DressingAsTheEnemy stunt enough times already to make any German [[JustifiedTrope leap at even the least suspicious of behavior]].
* In two of the [[MultipleEndings three endings]] to ''Film/{{Clue}}'', Wadsworth deduces that the cook used to work for Mrs. Peacock [[spoiler:and that Mrs. Peacock had killed her]] because Mrs. Peacock said that what the cook had made for dinner was one of her favorite recipes – "and monkey's brains, though popular in Cantonese cuisine, are not often to be found in Washington, D.C."
* In ''Film/TheFinalCut'', Creator/RobinWilliams' character concludes that a man he sees in a recording is someone he met years earlier when they were boys, because he cleans his glasses on his shirt. Most people who wear glasses will clean them on their shirt if a more suitable cloth is not available.
* Played with in ''Film/AFewGoodMen'' – a murder victim in Guantanamo Bay's military base in Cuba had supposedly received long-awaited transfer orders for a flight early the next morning, but had not packed by the time of his murder later that night nor called any friends or family back home to make preparations. When his commander is asked about this at trial, he quickly points out that there could be any number of explanations for those facts (maybe he liked to pack in the morning), and he can't be expected to explain them. However, the contradiction is enough to irritate the witness and put him on the defensive—[[XanatosGambit just]] [[ZigzaggingTrope as planned.]]
* ''Film/{{Gattaca}}''
** Towards the end [[spoiler:Dr. Lamar]] says he always knew Vincent was a "borrowed ladder" (genetic inferior with the false identity of a genetic superior) because a right-handed man doesn't pee with his left hand. This may be true more often than not but it's certainly not a biological necessity.
** Subverted regarded the murder subplot in the film. A potential suspect for the crime is dismissed because his genes bear no markers of excessive anger or proclivity to violence. This is all thrown out the window when it turns out he really did commit the murder [[spoiler:to protect his life's ambition, rather than through anger]].
* The Christian propaganda film ''Crime of the Age'' is full of this. A detective is called in to investigate the theft of a book at a bible camp and he's suspicious of everyone he questions because of a supposedly un-Christian thing they've done.

* Some examples from ''Literature/EncyclopediaBrown'' author Donald J. Sobol's less famous solve-it-yourself series for adults, ''Literature/TwoMinuteMysteries'', starring Detective (no first name given) Haledjian:
** Haledjian knows someone is the culprit because he claims that a cook in the kitchen was yelling and waving a bright red lobster before he was found murdered. The lobster wasn't supposed to be cooked yet, and lobsters are only red when they're cooked. However, that detail wouldn't be impossible, just weird. The back cover of a regular mystery might well say something like, "Why was the cook waving an already-cooked lobster before he was killed?" Another question is, was the cook yelling ''because'' the lobster had already been cooked?
** Haledjian knows that Nick the Nose, the informant, is lying (as he always is), because he claims that a dying Brazilian's last words were in Spanish, and the national language of Brazil is actually Portuguese. (Because the Brazilian couldn't be one of the many immigrants to Brazil from nearby Spanish-speaking countries. And because it would be impossible for a native Brazilian to speak his last words in a foreign language. And because it would be impossible for an Anglophone informant to simply ''mistake'' Portuguese for the extremely-similar-sounding and more commonly heard Spanish language.) In fact, depending on what he said, it could sound exactly the same in Spanish or Portuguese, especially from the mouth of a dying man (who presumably isn't speaking particularly clearly).
** One of the cases involved the apparent suicide of an actor and Haledjian claiming that the note left behind was a fraud written by an English rival of the deceased because the note used "theatre" instead of "theater" and other British spellings. (Because apparently, Americans are only supposed to use American spellings. And no one ''ever'' uses "-re" to refer to stage productions and "-er" to refer to a local multiplex.)
*** This one is particularly egregious: most actors, even American ones, probably ''would'' spell it "theatre", unless they were specifically referring to a movie house. In fact, [[Wiki/TVTropes This Very Wiki]] uses "Theatre" as the namespace for plays, not "Theater".
** Another case has Haledjian declaring someone's alibi faulty because the person identified the tune a band was playing as "God Save the Queen" rather than "My Country, 'Tis of Thee" (which has the exact same tune), and so knew about a British performing troupe being in town. Many American Creator/GilbertAndSullivan companies play "God Save the Queen" before performances, and as a StandardSnippet, it's ''always'' "God Save the Queen." Even worse, the actual ''name'' of the tune is "National Anthem."
*** [[RunningGag And again]] involving another race runner, where "[[CoveredUp The Theme from]] ''Franchise/TheLoneRanger''" is identified as "The William Tell Overture". Apparently Sobol liked this one.
** The alleged murderer claims to have not visited his friend for days, but is caught because he leapt over the freshly-painted stairs and knocked on the window set into the door rather than the freshly-painted door itself. (Because it's not like fresh paint ''looks'' and ''smells'' like fresh paint, especially fresh ''white'' paint. And because it's not like some people leap over stairs as a matter of course, or like knocking on a window is often simply ''louder'' than knocking on a heavy door.) This is one of the many cases that were recycled for Encyclopedia Brown to solve.
** An English professor's suicide note is considered fraudulent and a product of foul play because it contains a split infinitive. (Because English professors always follow grammatical rules, even when distraught and suicidal, and all English professors accept "don't split infinitives in English" as a rule.)
*** A variation on this has actually [[TruthInTelevision happened in real life]]. An old, very cultured, French widow was found murdered in her villa, with a note on the wall in blood that implicated her gardener. However, it said (in French), "Omar m'a tuer" ("Omar to kill me") instead of the grammatically proper and phonetically identical "Omar m'a tué" ("Omar killed me."). They still haven't solved the case.
*** One also has to wonder why a dying person, writing in their own blood, would bother to write more than 'Omar'. Why not throw in the murder weapon, time of the event, and description of the room while you're at it? [[TabletopGame/{{Clue}} "Omar killed Me in the Villa with..."]]
*** An inversion of that was actually used as a clue in the book ''Something Wicked'' by Alan Gratz. The name of the victim's son, Malcolm, is found written in blood next to the body... except everyone, including the victim, called his son Mal, and why bother with the extra four letters if you're dying and the first three are sufficient?
*** A situation that was almost exactly the same cropped up in one of Jim Sukach's Dr. Quicksolve books. The suicide note said "if I were him" instead of "if I were he".
*** Similarly, in an Encyclopedia Brown case, a note about who was supposed to receive some calendars couldn't have been written by a math teacher because it says "divide the calendars by 1/2", which would actually be multiplying by 2, because math teachers never make mistakes in grammar or use common English-language phrasing fallacies outside of the context of the classroom.
** Haledjian also dealt with the rather more plausible inversion, where the suicide note was in perfect grammatical English despite the dead man being an uneducated Italian immigrant who read the news in an Italian-language newspaper.
*** A similar situation occurs in ''Literature/ASeriesOfUnfortunateEvents''. GrammarNazi Aunt Josephine's alleged suicide note contains several grammatical errors, leading the Baudelaire siblings to believe it is a forgery. It turns out that [[spoiler:the note was genuine, but the ''suicide'' was fake, and the errors were a coded message to that effect]].
** The suspect claims it is his first time in the victim's house, but when a doorbell rings, he knows to answer the back door. (Because nobody can ''hear'' where a given sound is coming from, and it's certainly not that front doors often always have a double ring (ding-dong) and back doors a single ring (ding). And because there's no way at all the suspect could be from, live in, or have lived in a town where it's customary to do everything at the back door except on special occasions.)
** The painting's owner claimed to be getting dressed to investigate the disturbance, with his right leg in his pants and his left leg out. (''Everybody'' always gets dressed and undressed left-leg-first. Didn't you know that?)
** A criminal's itinerary read "Palestine" instead of "Israel", thus revealing he wasn't ''actually'' going to the Middle East as his girlfriend claimed. (Not a lot of tolerance for potential political differences.) Encyclopedia Brown got this one too. His dealt with a list of international locations which turned out to be cities in Texas, and "Palestine" was the clue.
*** Ironically, a better inconsistency that wasn't part of the solution but was instead mentioned earlier by Mrs. Brown was that the list mostly had individual cities (London, Paris, Odessa, etc) but didn't list a specific city in Palestine.
** Sobol really really liked making the solution hinge on phrasings that can be either of two different sets of words, in both Encyclopedia Brown and 2-Minute Mysteries.
*** "An arrow flight away"[=/=]"A narrow flight away": The detective was specifically looking at the flight of stairs when he said it and the suspect still replied "then why don't you go ''outside'' and look for it?", rather than "upstairs", revealing that he knew that the stolen diamond had been shot out of the house with a bow and arrow.
*** "Flawless"[=/=]"floorless" The police have confiscated a car whose floorboard was used to smuggle drugs. Haledjian is trying to catch the crooks by posing as car salesman "Flawless Phil". He mentions to one prospective buyer that "the interior is floorless"; when the buyer walks away, Haledjian orders him arrested on the grounds that had he been innocent, he would have heard "floorless" as "flawless", the slogan of the lot. While there are accents that make 'flawless' and 'floorless' sound similar or even the same, there are many more where they are quite distinct. And in either case, isn't it possible that the guy ''just didn't like the car'' or perhaps he had to take a dump? (In this case the guy didn't help his case by acting really nervous.)
** Two Minute Mysteries also recycled the "Frisco" clue discussed in the Encyclopedia Brown section above.
** In one of the Two-Minute Mysteries, the suspect was caught after Haledjian said the (diamond?) was hidden in the cupola because the murderer was the only one who ran up towards the attic instead of to the kitchen. Because only a murderer could know that a cupola (usually "KOOP-ul'uh", but the pronunciation varies by person enough that "kupp-ola" wouldn't be suspicious) was a term for the little domed thing on top of the house and not just an annoying term for a cappuccino maker, that only someone who had killed the house's occupant would assume that the stairs going up lead to the roof level, and that it's impossible to see a cupola from outside the house.
** In one case, the question of whether or not a ring bearing a very valuable jewel was stolen or legally bequeathed comes down to the accusing party's testimony. She says that when she saw the deceased for the last time (when he supposedly bequeathed it to her), he was reading a book and wearing the ring on his right hand, so when he turned a page the gem flashed brilliantly. Haledjian figures that the 'witness' is lying because the dead man was reading a book written in Hebrew before he died—and Hebrew is written right to left. The man would have been turning the left page with his left hand, not the right page with his right hand... But most people turn the page with their ''dominant'' hand, regardless of direction. If Haledjian had been correct here, then people would use a different hand to flip back through a book than to flip forward through it. Even animators knew this wasn't true.
** Overall, though, this series tends to deal with it in a better way than Encyclopedia Brown, in that the stories are SO short that Haledjian only has time to declare that he believes the suspect is ''lying'', not necessarily ''guilty''.
** Sometimes, Haledjian completely disregards [[HanlonsRazor sheer stupidity as an answer]]. In one mystery, he was on his way to a BBQ when the host was found murdered. His neighbor came over, saying he heard his wife scream in horror, and during the interrogation, spotted the wife's pearl earring in the grill and reached his hand in to retrieve it. The detective told him that he obviously planted the earring because, despite having just arrived, he knew that the coals were cool enough to plunge his hand into them. Apart from the fact that coal visibly whitens when heated and that people can sense heat when standing next to hot coals, does he ever consider the fact that the guy could have just been an idiot?
** In one case, the head of an orchestra had two skilled violinists and had to decide which would play a solo on opening night. He picks A about five minutes before the performance is meant to start. When he goes to get A, he finds A has been killed, and then has to pick B. Haledjian decides that it must have been B who did it, because B walked onto the stage, sat down and began to play, when he should have tuned his violin and rosined his bow first. Like it's totally unthinkable that someone with an equal chance of getting a part would get themselves ready to play it, especially if the choice wasn't going to be made until about five minutes before it was meant to begin.
*** Also, violinists seldom rosin their bows on stage in general.
** In one, Inspector Winters asks for bicarbonate of soda for an upset stomach while in a bakery. The baker says she doesn't have any; this leads the detective to deduce that the bakery must be a front for smuggling, since bicarbonate of soda is baking soda and no real bakery would be without it. Except there's the possibility that the baker was unfamiliar with an antiquated term for baking soda (even more egregious today than when it was originally written: many modern ''chemists'' might find the term unfamiliar, since the proper scientific terminology has been "sodium hydrogen carbonate" for ''decades'', and was "sodium bicarbonate" rather than "bicarbonate of soda" for some time before that). And then there's the possibility they ran out of baking soda using it to, you know, bake.
* There was one book of "Solve it yourself mysteries" intended for kids which seemed to do something with the trope while inverting it with more common examples (e.g. saying a nurse was likely sending threatening calls because there were babies screaming in the background, puzzles about time zones, etc.). One case hinged on "I was woken up by thunder and then saw a man stabbed during the lightning" because lightning always comes before thunder. Yeah, makes sense, but apparently, there was only ''one'' strike of lightning.
** Another case from the book had a murder take place at a country club wherein someone was pushed down a hill and broke his neck in the fall. The tennis player who reported it was apparently the murderer because he had a grass stain on his shoes and of course, tennis players would have different shoes for tennis than walking around in the grass. Yeah, you'd have a point there, since many tennis players keep a separate pair of shoes specifically for tennis the way people do for a lot of sports, but apparently, the grass stains ''certainly'' [[SarcasmMode couldn't have come when he ran over to see if the victim was okay or not]]. (In real life, it'd have been ''more'' suspicious if he stopped to change his shoes like the detective thought he would.)
** Another one had a victim killed by having a heavy clock dropped on his head, and there were two murderers. All three suspects claim it was most likely an accident. Person #1's alibi was that he was watching a TV show at the time of the murder. Person #2 hears something fall to the floor from down the hall and runs to investigate, and person #3 was out smoking, then walked in and simply found #1 and #2 standing over the body. The detective says that Person #1 and #2 are guilty for several reasons. One, the clock stopped at 8:51 and no TV show ends at 8:51. This is an analog clock (the stories were written in the 70s) and evidently, there's not the possibility that it might have been simply ''running slowly'' (or that the clock's hands got jarred by the impact). The second one also apparently couldn't have heard the body from the other side of the hall, but it's actually not impossible to hear something heavy fall to the floor, especially if it's a clock heavy enough to kill someone.
** Lampshaded in one story where the detective is listening to someone's testimony on a crime, and mentions it won't stand up in court because he was telling the story as he saw it, through the mirror of a car.
* Creator/IsaacAsimov {{lampshade|Hanging}}d this in one of his stories, in which a character points out that in most detective stories all the detective's deductions could easily be picked apart by a competent defense lawyer and it's a good thing the detective is always able to use their deductions to make the perpetrator panic and incriminate themselves before they go to trial. That didn't stop him from flirting with the trope himself, though.
** In one Creator/IsaacAsimov short story, two similar-looking girls work in a library. One of them murders the other, but claims she has an alibi—she was accepting a book return from a student at a certain point before the murder. The Sherlock determines that she was lying, and in fact the other librarian accepted the book, because the murderer didn't remember the name of someone who returned a book. He shared a name with the author of a book ''very'' well known to any librarian in that university. Not much evidence, but since she confesses later, that's what would matter in court.
*** It wasn't just a locally well-known author, but the author of THE chemical reference, period. A professional chemistry librarian could no more forget the name "Beilstein" any more than a conductor could forget an applicant named "Ludwig van Beethoven".
*** Unless she was distracted, or just not particularly amused by the coincidence (however, since an emphasis is made on the girl ''smiling'' at hearing the name, both can be argued against). A Black Widowers story, "Spell It!", removes this possibility by having the man make a ''huge deal'' about his name being famous after a bookstore clerk innocently asks him to spell it. Of course, this version discounts the fact that two different people may spell similar-sounding names differently, thus leading a clerk to ''always'' double-check. This was a Black Widowers story, so the solution wasn't claimed as definitive—see below.
** Asimov wrote a whole slew of anthologies in the ''Literature/EncyclopediaBrown'' vein, wherein the members of a men's club would discuss various mysteries during their monthly dinner at their favourite restaurant, until their waiter provided them with a solution. His use was usually more justified, as, not adhering particularly strictly to the ''Literature/EncyclopediaBrown'' formula, the ''Black Widowers'' were usually pursuing a problem purely as an intellectual exercise, and more often than not, their goal was not to find a legally substantial argument, but just to construct ''any'' explanation that was entirely plausible and fit all the facts. (For example, one of the "cases" they tackle is to work out the subject matter of [[Literature/SherlockHolmes Professor Moriarty]]'s doctoral thesis.)
*** One of those stories inverted this trope by having the shaky evidence (that an accountant would associate the phrase "half past eight" with 8:50 since "eight and a half dollars" is $8.50 and accountants are marinated in money) given to a defense lawyer with an innocent client, so that he can use it to impeach an otherwise unshakable witness. The story was written at a time when digital clocks were still relatively new.
*** In the above story, "What Time Is It?", the characters admit that, while not conclusive evidence, this could be used by the guest, a defense attorney, to sow reasonable doubt in the minds of the jurors, allowing his client to be acquitted.
** Asimov also wrote a Union Club short story called "No Refuge Could Save", in which a man is identified as a German spy because [[SecondVerseCurse no American could possibly know all four verses of the Star Spangled Banner]].
*** Questions like this ''were'' actually used to find spies, at least in the movies, but it was usually reversed—failure to know the National Anthem or last year's World Series champion was considered "evidence" of espionage. Asimov's joke was that spies who knew about that system would ''over''prepare. In addition, [[WriterOnBoard Asimov had very strong feelings]] about the song, and considered it a tragedy that Americans didn't know it. He also wrote an essay about the importance of all four verses.
** Asimov had a habit of writing mysteries in which the detective is either an amateur or a professional outside of his jurisdiction, so that he has no legal weight behind his investigation. The detective has a Eureka and figures out whodunit, but the only way to convince the ''real'' authorities to even arrest the criminal is to resort to PerpSweating. The novels ''Murder at the ABA'', ''The Naked Sun'', ''A Whiff of Death (''aka ''The Death Dealers)'' and ''The Robots of Dawn'' all fall into this pattern. Darius Just, the hero of ''Murder at the ABA,'' makes a point of saying that his deductions were all founded on circumstantial evidence and a defense attorney would never have let his argument stand.
** In one of Asimov's short mystery stories, the culprit is a Québécois person using a false identity of an American. The detective tricks him into revealing his true identity by asking him to write the word "Montréal", and he writes it with an ''accent aigu'' on the e, whereas someone who only spoke English wouldn't spell it that way. To rule out innocent explanations for this information, the interrogator establishes by prior questioning that the American identity doesn't speak a word of French. Never mind that you can know about the etymology of words without also knowing the language the word was originally from, or that he might have seen someone else write it "Montréal" and followed suit.
** ''Justified'' in his short story ''The Singing Bell'': the evidence against the culprit would never stand in court, but the detective explicitly states that he's just looking for enough evidence to convince a judge that a mind probe is justified. This can, by law, only be done to a particular individual one time in their life, so it's only performed for very serious crimes (like murder) when there's very good reason to suspect the accused is guilty, but not enough evidence to actually ''convict'' them.
** In another short story, ''The Dying Night'', featuring the same amateur detective, he is able to figure out who the killer is not only through very circumstantial evidence, but one which wouldn't even work today due to ScienceMarchesOn. In this story, the victim was killed because he had discovered the secret behind teleportation, and the killer wanted it for himself. When they entered the bedroom of the victim, everyone sees the sun shining through a window. One of the suspects, who had spent the last 10 years living on Mercury, leaps to the window in apparent fright, and spots the exposed film containing the information on teleportation. The detective surmises that he is the killer, since only he would hide exposed film out a window at night, forgetting that the sun would eventually rise. At the time the story was written, it was believed that Mercury always had the same half facing the sun. Asimov admitted the gaping plot hole this created in his story, but since the discovery had been made long after the story was published, he didn't see any point in trying to fix it at that point.
*** Ironically, while Mercury does rotate, it does so ''very slowly'', meaning the story could actually work if the suspect just wasn't expecting dawn to come so ''soon'' rather than never.
** Lampshaded in one of the ''Literature/LuckyStarr'' books, where Bigman suspects a blind man of being a spy and not blind at all. His arguments are that, like in the above Encyclopedia Brown case, the man is sitting with the lights on, and that he noticed when Bigman turned the lights off. However the man provides perfectly good explanations; he realized Bigman turned off the lights because he heard him tiptoeing toward the wall and his guide dog going to sleep, and as for the lights... well, it doesn't matter to him, but it would probably matter to any friend who might come to visit.
* A series of short plays for kids published in the UK featured a detective with the {{catchphrase}} "And I can prove it, because you made four silly mistakes". The mistakes rarely proved anything. (In fact, one of them was the [[TropeNamers fallacy namer]] for NoTrueScotsman; a character during the Jacobite Rebellion is exposed as an English spy because, amongst other things, he puts sugar on his porridge...)
* One short story in the anthology ''Creator/AlfredHitchcock's Sinister Spies'' is called "[=QL696.C9=]", by Creator/AnthonyBoucher. It's about a librarian who was killed, leaving a the titular mysterious sequence of letters and numbers nearby. At the end of the story, the detective gathers the suspects in the, um, library in the traditional fashion,[[spoiler: declares that the code was probably a library subject reference number, and starts to look it up.]] He's interrupted by the need to keep the murderer (a spy), from killing herself with the pistol she hid in her blouse. Turns out he knew it was her as soon as he figured out what the code was for, as the killer had the only name that was a noun, and the whole library scene was just to flush her out. FridgeBrilliance kicks in when you realize that the detective needed something from the suspect to avert this trope, since there's all sorts of perfectly good reasons a librarian would have to write down a Library of Congress reference code [[spoiler:for swifts]]. Ironically, the anthology in question comes up when you search the [=LoC=] for the code.
* Creator/WoodyAllen, in one of his books, wrote a parody of the detective-catching-one-mistake trope (''Match Wits with Inspector Ford''). The situations and answers were all absurd. For instance, a kidnapping victim returns home by asking his kidnappers if he could go to a football game that he only had one ticket for. The detective figures out that he's in on it with the kidnappers, because his parents are in their 80s and he's 60 years old, and "nobody would kidnap a 60-year-old man, as it makes no sense."
* Creator/JohnDicksonCarr specifically warns aspiring mystery writers about this kind of clue in his essay "The Greatest Game in the World." Of course, if you do what he advocates, having guilt depend on a series of clues rather than just one, you won't have that problem.
* ''Uncle John's Bathroom Reader'' had a series of simple mysteries featuring Leslie Boies and her companion, Steve. In one story, Steve tells Leslie about a man whose life was saved because the night watchman at the factory he owned told him he dreamt the train he usually took was going to crash. So the man waited for a later train, and sure enough, his usual train crashed. Leslie comments that the watchman should be fired, because if he dreamt about the train, he must have been sleeping on the job. Because he couldn't have had the dream when he was back at home, clearly. This is a variant on the tale that actually ''introduces'' the element that makes this qualify; in other versions, the dreamer specifically states that he had the dream at a time when he was at work.
* In one of the stories in Maurice Leblanc's Literature/ArseneLupin book ''The Eight Strokes of the Clock'', Lupin determines that one of the extras in a silent film is infatuated with the leading lady solely from the out-of-character lustful gazes he casts upon her in the film. (These days, we'd just call that "bad acting".)
* In one of the original Literature/MissMarple "Tuesday Night Club" stories, Miss Marple bases her conclusion on the fact that the gardener wasn't really a gardener, because he was working on Whit Monday. JustifiedTrope, because she's not trying to convict him, just solve the crime as a puzzle.
* Discussed and then averted in the novel ''The Franchise Affair'' by Josephine Tey. The novel is about two women accused of kidnapping and enslaving a school girl and the attempts of their solicitor, Robert Blair, to defend them. Midway through the novel, the womens' solicitor discovers a discrepancy that can be used to cast doubt on the girl's story (she could not have seen the view out of the attic window that she describes). However, Blair realises that a clever prosecution lawyer can argue around this and even if the women are let off on this evidence, the taint of the accusations will still hang over them.
* Another juvenile book series titled ''You Be the Jury'' by Marvin Miller worked on this trope. You, the reader, were the jury and had to decide guilt or innocence based upon the case testimony and three pieces of evidence. In short, the defendant was guilty or innocent based on a contradiction within the testimony and evidence. One example was a case involving a radio DJ being kidnapped as revenge for publicizing the bad service of a local roofer. It turns out that the DJ faked the kidnapping as a publicity stunt as one piece of evidence was a photo of him after getting away from his kidnappers three days later. He was clean-shaven and the solution argues that he should have had a three-day beard.
* Subverted in ''Death on the Way'' by Creator/FreemanWillsCrofts. The police prove that one of their suspects faked his alibi for the time of the murder, and consider that this is sufficient evidence to arrest him. It turns out he isn't the guilty party—when he realised he couldn't prove his innocence, he panicked and constructed a false alibi.
* In ''Literature/TerraIgnota'', Papadelias, the cop who brought Mycroft in after Mycroft's two-week-long murder rampage, has known for years that there is something off about Mycroft's case, based mostly on how Mycroft seemed to be in two places at the same time while commiting his crimes. Every time they run into each other, he quizzes Mycroft on the timeline, trying to find discrepancies. Mycroft always has a correct and plausible answer. [[spoiler:Papadelias is right, though. Mycroft is hiding his lover and partner in crime Saladin, who commited half the murders.]]
* The short story collection ''Inspector Forsooth's Whodunits'' sets out to very deliberately [[AvertedTrope avert this trope]], even citing the classic example of "the English professor who 'committed suicide' and left a note filled with grammatical mistakes." Author Derrick Niederman certainly succeeds--the mysteries are ''intense'', and require disproving alibis based on evidence, codes, and occasional outside knowledge (various cases include needing to know [[spoiler: state tax laws, the dates of zodiac signs, and the intricacies of a particular Chopin piece]]).

[[folder:Live Action TV]]
%%* ''Franchise/PerryMason'' is absolutely made of this trope.
* Occasionally ''Series/{{Cracker}}'' falls victim to this trope, with profiler Fitz often using "Encyclopedia Brownisms" rather than genuine psychological insights. In one episode, he deduces that someone is the murderer, as they claimed to be a student and "you don't dress like a student" (because obviously, all students dress exactly the same way). In another episode, he not only deduces that someone is a closet gay, but also his alibis, because when questioned he said "I was at home with my girlfriend" rather than "I was at home with Lesley"—thus showing he was afraid of saying that his girlfriend's name was a potential man's name and letting Fitz think he was at home with a man (because, of course, everybody normally says "I was at home with [name]" to complete strangers, despite the stranger not having a clue who [name] would be).
** In cases like these, it's hard to tell if Fitz actually deduces from these facts, or if he's got a hunch and is using some detail to prod (or, rather, ''bulldoze'') a suspect's nerves. There are instances where his 'gotchas' are shown to be ineffective, immaterial or just plain wrong, and he merely forges on until he gets a hit. There is no denying his huge deductive leaps from small details, however.
* Played for laughs in an episode of ''Series/{{Blackadder}} Goes Forth'': Blackadder reveals he discovered Nurse Fletcher Brown was a German spy when he asked her if her well-educated boyfriend had been to "one of the great universities: Oxford, Cambridge, or Hull. You failed to spot that only two of those are great Universities." To which General Melchett, a Cambridge man, replies, "That's right! Oxford's a complete dump!"
** This was actually a playful poke between the actors; Creator/StephenFry (Melchett) is a Cambridge alumnus, while Rowan Atkinson (Blackadder) graduated from Oxford.
** Not to mention, of course, that Hull University didn't even exist until 9 years after the end of WWI.
** And, of course, it was eventually revealed the nurse was innocent (at least of passing on the information that made General Melchett suspicious in the first place), and the episode ends with Captain Darling scrambling to reveal it (just to make Blackadder look bad) as Blackadder tries to stop him.
*** She doesn't deny it at all, and pretty much confesses without actually saying she did it, giving all the traditional 'I thought you loved me' nonsense. So apparently she was also a German Spy?
* In early episodes of ''Series/StarTrekDeepSpaceNine'', Dr. Bashir often mentioned the one mistake he made on his final Academy exam: he mistook a preganglionic fiber for a postganglionic nerve. This was all that kept him from graduating valedictorian. But in the episode "Distant Voices", an alien in Julian's brain points out what viewers with medical training (including writer Rob Wolfe's wife) caught right away—a preganglionic fiber and a postganglionic nerve are nothing alike. The alien accuses Julian of getting it wrong on purpose, which later proves to be true, though for a different reason. If Encyclopedia Brown had been security chief of ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'', we might have learned about Bashir's BigSecret (he's [[spoiler:genetically enhanced]]) four seasons sooner...
** Also, there was an episode of ''Series/StarTrekTheNextGeneration'' where hearings were being held of Starfleet officers out of fear that there was a Romulan spy on board the Enterprise. One officer questioned was revealed to have falsified some personal information claiming he had a Vulcan grandfather, when the grandfather was actually Romulan. Everyone, particularly the witch-hunter who started the hearings, took that alone as just-about-proof that he was the spy they were searching for, but Picard recognized that it hardly counted and worked to get the hearings stopped.
** One of the books had a Romulan spy hidden among the crew, and the "clue" that lead to his unveiling was that fact that "he separated his food into separate piles, so they did not touch, and ate them one pile at a time." It was explained that this was how Romulan children are trained. Of course, [[SarcasmMode no other race in the universe]] could have that tradition[[note]]though on the other hand it would be easy for a Federation computer to check if any of the supposed cultures of the people on-board have that tradition, with any discrepancy causing suspicion right up until it hits the other issue[[/note]], or people who just don't like having their food mix on their plate.
** Actually deconstructed in an episode of ''Series/StarTrekVoyager'' of all places. A copy of the Doctor finds himself in a museum seven hundred years into the future, a museum dedicated to the "Voyager incident," which claims the ship caused an entire civilization to be conquered by another race. The Doctor tries to explain what actually happened: Voyager was just making a trade deal for fuel that was misinterpreted to be a weapons deal. The Doctor could prove it wasn't Janeway who shot the first civilization's national hero, but an ambassador from the second race. However, it was pointed out proving who fired a single weapon in what circumstances doesn't really change the broad strokes of the history the "oppressed" civilization [[PoliticallyCorrectHistory wants to maintain]]. He does succeed in revealing the deception to the general population in the end, though.
* ''Series/{{Columbo}}'' did its best to avoid the pitfalls of this trope. Typically, Columbo's suspicions are often piqued by this sort of clue, and he always opens his investigation by giving his suspect an opportunity to provide a perfectly reasonable explanation for it. Several "Just one more thing"s later he's backed his suspect into a corner that they can't wiggle out of.
** Still shows up in the first regular episode "Murder By the Book", where Ken Franklin, half of a mystery writing team, sneers that Columbo doesn't have anything concrete linking him to the murder if his partner Jim Ferris—just a motive, the fact that he took out a life insurance policy on the victim, the fact that someone else was murdered shortly afterward who he claimed not to know but in whose house was found a book with a personal autograph in it, and such odd behavior as opening his mail shortly after finding the body on his lawn, and withdrawing a large sum of money out of his bank account and redepositing it the next day. And Franklin's right, these things are all circumstantial evidence. Then Columbo points out that he found a vague story outline in the victim's office; apparently Columbo's (accurate) reconstruction of the murder matches one of the thousands of rough story ideas that Ferris had been scribbling down over the past couple of decades. Franklin immediately gives in, despite this being easily the ''weakest'' piece of evidence presented thus far.
*** The worst part of the episode, though, is that Columbo finds the minor flaws in the alibi but misses what should have been a fatal flaw in Franklin's plan—the police identify that his phone placed a call to Ferris's wife, but they fail to look at the time of the call and realize that it was the phone call where she heard her husband get shot, and not the call that Franklin had placed to her house (from another phone) ten minutes or more before the murder.
* An episode of ''Series/{{House}}'' ("The Tyrant") has House confront Wilson's neighbor, an amputee who claims to have lost his arm in Vietnam. House deduces from various clues that the man is a veteran of the ''Canadian'' Army, and calls him out as a fraud—only to be told that although Canada didn't take part in UsefulNotes/TheVietnamWar, they did send troops to Vietnam to enforce the Paris Peace Accords, which is how he lost his arm in a landmine incident. It's also a straight example as Canadian troops ''did'' fight in Vietnam: [[https://en.wikipedia.org/wiki/Canada_and_the_Vietnam_War#Canadians_in_the_U.S._military 30,000 soldiers in all]].
* ''Series/MurderSheWrote'' usually avoids this trope. One of Jessica's most common lines after a EurekaMoment is "I think I know who the killer is. The only problem is, how to prove it…?" Not so much in Season 5. (Coincidentally or not, these are the first eps after the 1988 writers' strike.) They had several eps where the guilty party knew something that anyone might have guessed. Case in point: In "Smooth Operators", the murderer knew that a bum was using a newspaper as a blanket.
* Many episodes of ''Series/{{Monk}}'' have Monk using this kind of evidence to determine the murderer from the start. One of the more common formats to an episode is that Monk will point out a string of these kind of things which prompts either the police or the suspect to point out that they're flimsy and not real evidence, often making up a plausible explanation as to why things might have happened in a strange way and often Monk will concede that they have a point. Instead, Monk uses these to figure out of a crime scene is suspicious enough that it's worth investigating for murder (as opposed to a staged suicide) or who's the most likely culprit and thus who he should focus his own investigation on. When he gives these lines of thought to the police, they're most often only used to establish credibility in his theory so that they're more likely to help find concrete evidence.
** For example, in "Mr. Monk and the Birds and the Bees", sports agent Rob Sherman has made it look like he shot and killed a burglar who apparently broke into his house and killed his wife (the trick is that he shot the "burglar" with a semi-automatic and the wife with a revolver, then planted the revolver on the "burglar", making great use of a DeceasedFallGuyGambit). Monk suspects Sherman is lying because he gave the alleged invader one single shot, instead of unloading his gun on him in a fit of rage and fear like someone would do in a situation like that. Further evidence is that the "burglar" owned a .22 caliber (which he left at home), the revolver found on the body was a .38 caliber, and there is no .38 caliber ammunition in his apartment.
** At least in that instance, the suspect did indeed kill the guy and challenging his version of events would indicate murder. In "Mr. Monk Goes Back to School," Monk zeroes on science teacher Derek Philby for no other reason than he found evidence he hid his wedding ring in his wallet—which meant he was having an affair and lying about it, making him suspect number one in the death of another teacher whom the police assumed (and Monk couldn't prove otherwise) committed suicide. (Although this and the previous entry could possibly be explained by Monk's feelings for his own murdered wife.)
*** Note that Philby is a ''science'' teacher, so presumably he teaches labs as well as lectures. For many lab activities, wearing jewelry isn't safe or appropriate; although a wedding ring is unlikely to hinder its wearer's handling of chemicals or dissection tools, a teacher might well remove it to set a good example of laboratory dress codes in front of his students.
** In "Mr. Monk Goes to Vegas," Stottlemeyer gets to be a DrunkenMaster when he realizes he solves a murder made to look like an elevator accident because of a contradiction in two tabloid photos, namely, the fact that the earrings the victim was wearing when she was getting onto the elevator were not the earrings that were found on the body when the elevator stopped, proving that a BodyDouble was present in the first photo.
** In another episode, Natalie's parents talk about a couple of friends of theirs who died in a car accident. When Monk hears that the car involved was a British Morgan, he becomes suspicious because the British drive on the left, and this doesn't square with the positions of the bodies at the scene. Apparently, Monk doesn't know that most British car manufacturers, including Morgan, make left-hand-drive versions of their cars for countries that drive on the right.
*** What's more, it really beggars belief that the crime scene investigators, who had the car and the bodies right in front of them, failed to notice this. The PoliceAreUseless.
* ''Series/{{Psych}}'': This is entirely how Shawn Spencer works. He figures out ''who'' did, and in some cases, ''how'', then has to prove the ''why''.
** Of course, the whole point of the show is that he actually claims to have received the information from his psychic powers. Instead of "This spot on your shoe proves you did it", it's more a case of "I can sense that you did it, oh and here's a spot on your shoe that backs me up." Whether this makes a difference to the juries in this show's universe is unknown.
** The fact that he has to point out the actual clues in order to get the cops to believe him in the first place indicates that yes, the evidence is what matters. Shawn's visions are pretty obviously not part of the legal proceedings, they're just the mechanism by which the cops find the hard evidence they need to prosecute.
** It was mentioned in an episode that they have something like an 85% conviction rate for cases they're involved in.
* Shows up quite a lot in ''Series/JonathanCreek'' (which was originally conceived as a British ''Series/{{Columbo}}'', after all). For example, from the fact that a piece of film supposedly secretly filmed by a stalker from over a tall fence used a pan instead of moving sideways, he deduced that it was taken by a short man standing on a box, and as the subject's manager was a short man, therefore it must have been him.
** They sometimes try to justify this by having him say something like "I don't know, it could be just a coincidence, but..." and wait for this to intimidate the accused to [[SayingTooMuch blurt out]] [[INeverSaidItWasPoison more definitive proof]].
* The Creator/{{Nickelodeon}} series ''Series/TheMysteryFilesOfShelbyWoo'':
** Shelby once identified a kidnapping suspect by breaking his alibi; he'd claimed he was at the movies around 8 or so but his ticket stub was for a 5:15. The suspect got irritated that she was going through his things and it was pointed out the evidence was not sufficient to point to his guilt—then he's identified based on his strange habit of drumming his fingers on his briefcase, making the same drumming sound as heard over the kidnapper's ransom call.
** Another ep had Shelby try to identify a suspect in a smuggling case by the sound of his whistling a particular tune. She told DaChief it had to be the musician who performed a concert in town whose song the suspect was whistling; DaChief points out that a lot of people attended that concert and would have found the song catchy. A guy whistling that same tune walks past them and DaChief smugly points and goes "See?"
* In ''Series/SevenDays'', there is an episode where some woman named Delores threatens over the phone to cause catastrophes unless Frank does as she says. Each time he performs a task, she answers a question. One of the question was about who won a certain year's sports championship. She answers correctly—this proves she's really a man impersonating a woman since Delores claims to know Frank personally and Frank has not known any woman who could correctly answer that question. The other possibility is "she" was either lying or delusional about her connection to Frank. Incidentally, this turns out to be true: [[spoiler:Dean Loris doesn't know Frank; he was a homicidal disgruntled ex-NSA employee jealous that he wouldn't get to be the first Chrononaut and wanted to humiliate Frank for doing what he never got the chance to do.]].
* On ''Series/{{CSI}}'', Brass once grew suspicious of a grieving husband saying "[[SuspiciouslySpecificTense I loved my wife]]" as she was carried out by [=EMTs=] after a supposed bathing accident, but at the time since it was just a passing hunch, he doesn't seriously investigate the matter until it comes up again later. He still has to get the lab to find more definitive proof of foul play before he could do anything substantial and the criminal wasn't arrested by the end of the episode (though the raised suspicions were enough for the wife's life insurance company to repossess the husband's newly-bought Ferrari).
** In another episode, while searching the house where the female victim of the week lived alone, Sara dramatically announces "the toilet seat is up—a man was here!"... without even entering the bathroom to check if maybe the victim had been vomiting in the toilet (they'd just found a lot of spoiled food in the fridge, after all), or whether she'd been interrupted in the middle of cleaning the bathroom, etc.
** This particular Trope is used ''a lot'' throughout the franchise. It's zig-zagged in that more solid evidence is what makes the conviction, but what more often than not drives the police into checking out a suspect is how some minor fact doesn't "feels right" to them (let's just say that if they start giving you sarcasm while interrogating you, you're better off confessing and hoping to high hell that the evidence saves you). Some arcs, however, have also showcased that apparently open-and-shut cases have gone on for as long as they did because the investigators allowed their personal interests to cloud their thoughts and taken any contradiction as damning evidence.
* ''Series/CriminalMinds'': Almost every profile, leading to several false arrests following generic descriptions. This is why profiles are not admissible in court for many jurisdictions. Most episodes end with perp sweating for confessions or real evidence to get around this. The truly strange thing is that even though they are fully aware their generic descriptions are often very wrong to start with, they get extremely annoyed should someone cast doubt when they make a prediction.
** Hotch actually says in one episode that the team's only job is to win an arrest—whether or not they've gathered enough evidence is "for the courts to decide". Considering the standards for an arrest can be as flimsy as a contradiction in the story, the team practically lives on this trope.
** Occasionally played with in the show, such as in "Doubt". The guy they arrest is [[ObviouslyEvil obviously the killer]], but he doesn't confess and they have no real evidence against him besides the profile, so they're forced to let him go (the fact that a [[JackTheRipOff Copycat Killer]] attacks while he's in custody helped).
** The team will often catch the perpetrator in the act of attacking their latest victim, thus enabling the real evidence to fall into their lap. The catch is that some episodes will point out how they don't have enough evidence for a warrant and need a pretext to bust into the suspect's property but in most cases, the mere identification of the most likely perpetrator cuts to a scene in which SWAT is breaking down their door.
** Another ep had the profile as the primary evidence against an amnesiac suspect since they caught him at his home and not in the middle of trying to kill his latest victim as per the usual formula. Lucky for them the suspect regained his memory and led them to another one of his undiscovered victims.
** One episode involved an [=UnSub=] who played a particular genre of music during his crimes. The team ended up dismissing one suspect on the grounds that he had been too young to be influenced by that music when it was popular. Apparently it's an iron-clad law that your favorite music ''must'' be the music that was popular while you were a teenager, and that no one ever prefers music from a previous era.
* ''Series/LawAndOrderCriminalIntent'': Detective Goren's entire Modus Operandi is coming up with contradictions to the suspect's story and using them to get the suspect to confess, often [[HollywoodLaw with their lawyer fully present]]. Like its predecessors, the suspect often gets so upset they decide to confess over their lawyer's objections.
** There's also the episode where a suspect, a substitute teacher, says he hasn't been to Egypt and learned about the new Library of Alexandria from a magazine article. When the suspect says that the library has state-of-the-art smoke detectors and Goren didn't see that detail in the magazine article, that the guy was lying becomes a major plot point. An arguably more likely explanation, that the substitute teacher was making a lame joke about the fact that the old Library of Alexandria burned down, isn't even considered.
* On ''Series/LawAndOrder'', when the police use contradictions in a suspect's story to solve the case for real, they're smart enough to use the it to gather more evidence to confirm the suspect's guilt.
** One exception was in "Savior": a teenager claims she tried to lift some family jewelry for her boyfriend but when the jewels were missing, he shot her and her mother in a rage. The DA points out she could have stolen the jewelry herself without inviting her boyfriend into the house and concludes instead that she was paying the boyfriend the jewelry to murder her mother and he shot her when the jewelry was missing.
** ADA Claire Kincaid once suspected a wife of the murder the husband had just been found guilty of. Her reasoning was that in a pretrial interview, the wife tried to cover for her husband's bank account withdrawals (which the victim was blackmailing him for) with a sloppily-crafted alibi. On the witness stand during cross-examination, she stuck to the same obvious lie with no elaboration; having known ahead of time the DA would ask about the money, she had more than enough time to come up with a more plausible explanation.
** In another episode, a husband's conviction for the murder of his wife hinged on the theory he stole a brooch from her body the police later found with his mother. The defense brings in identical brooches to challenge the DA to prove the one they have is the right one. The victim's lover identifies the brooch from an engraving she'd made on the back of it.
** In one episode, Cerreta and Logan interview a murder victim's family, and the son tells them that his mother ''wouldn't'' have killed his father, saying that he was with her at the time of the murder. Later in the episode, Cerreta wonders why the son didn't say she ''didn't'' kill his father, if they were together. Although the variation, while still a leap on the part of the detectives, is rather significant in that if someone is physically with you at the time of a murder, you know full well they couldn't have done it and thus have little reason to prevaricate.
*** Assuming, of course, that all the statements are logically interconnected, and the son didn't actually mean "She wouldn't kill him, ''and'' she was with me, anyway, so it's moot." Traumatized families of murder victims aren't always speaking in the most logical thought progression, and it seems odd to take their minor verbal flubs as greatly significant.
* Pops on ''Series/TheMentalist'' occasionally. Somewhat justified in that Patrick Jane is all about trusting his gut rather than relying on hard evidence and will usually find a way to lure a suspect into implicating themselves with ''real'' evidence once he's convinced they did it.
** However, one notable example occurs in an episode where Jane quickly convinces the cops that a notoriously stingy millionaire is the culprit because he offered a reward for info on his employee's killer. After 48-hours, with no actual evidence or success at interrogation, they are legally required to release him. But as the guy is leaving the building, Jane tricks him into correcting a mis-quoted line from Shakespeare, contradicting his earlier claim that he neither liked nor knew the material (relevant because the victim had been killed by someone she met in a chatroom on the subject). This single slip is treated as a decisive victory and the cops immediately take him back into custody as if they now have enough evidence to make an actual case against him.
** A variation of the old "I'm innocent" vs. "You can't prove that" giveaway is used in another episode when the main character sits down three suspects and declares that he's going to have them fingerprinted to see who accessed a certain company computer. Two of the suspects become visibly upset and protest that of course their fingerprints will be on it because it's a public terminal. The third suspect says, "Go ahead. It'll just prove that I'm innocent," which of course immediately arouses suspicion because only the culprit could know that their fingerprints won't be found.
* ''Series/{{Crownies}}'' features this when a teacher accused of having sex with a student claims that a note the student had in her possession was written to his wife years earlier. Conveniently, the note happens to mention a brand of alcopop that didn't exist at the time.
** The spinoff, ''Janet King'', has an inversion when Alex Moreno is on trial for sending a teenage girl he'd met online (actually an undercover cop) a text message asking her to perform a sex act. Moreno's defence is that he knew he was talking to an adult from the beginning. His reasoning? No real teenager talks about their parents in a chatroom without using some kind of chatspeak term. The judge accepts this and acquits him. [[spoiler:And then turns out to be a pedophile himself, with a long history of corruption.]]
* ''Series/TwentyFour'': in the first season, Jack is [[JackBauerInterrogationTechnique interrogating]] a businessman in his limo, trying to prove he isn't who he says he is while connecting him with the conspirators in the day's events. His initial "contradictions" are fairly shaky, such as why is an honest businessman is meeting someone in a garage unless the person was a criminal. The real clincher that he's a phony is when he tries to attack Jack with a knife he keeps in a secret compartment of the limo; why would an ordinary businessman who can presumably afford security carry a blade in his car unless the guy he was meeting with was a criminal? Perhaps the guy's just CrazyPrepared? In this case, it may have been as much about the knife itself as the fact that it was a specialized blade: a Microtech HALO that's something only a KnifeNut would procure.
* One case from Mathnet on ''Series/SquareOneTV'' involved a number of contradictions which made detectives Kate Monday and George Frankly suspicious of a kidnapping victim's involvement in the crime. In "The Problem of the Trojan Hamburger", amateur gem cutter Hans Ballpeen is kidnapped and the [[MineralMacGuffin Despair Diamond]] is stolen afterwards. Ballpeen manages to escape and explains that he was forced to cut the diamond. [[spoiler: Monday and Frankly are more than suspicious because of not one, but a number of contradictions in his account. First, Ballpeen was kidnapped first and then the diamond was stolen—it's reasoned that there's no point in kidnapping a gem cutter unless you have one to cut in the first place. Second, Ballpeen claimed he hadn't cut a diamond in years, which made the detectives wonder why someone that rusty would be kidnapped instead of someone more skilled. Third, Ballpeen doesn't identify the diamond as the Despair Diamond. That was considered odd since it was a world-famous diamond. Fourth, he claimed that he was released somewhere in the woods, hiked to a highway, and hitchhiked home. Kate Monday pointed out his boots were pristine and George Frankly reasons that anyone getting away from kidnappers would find first find a phone and call the police.]]
* Many perps in ''Series/ColdCase'' collapse and confess after being caught in a contradiction, no matter how petty, after having got away with it for ''decades''.
* Subverted on ''Series/MurdochMysteries'' when a caravan of gypsies are accused of burglary by the sons of several upper-class families who've been robbed. Inspector Brackenreid initially arrests the gypsies, but he later smells a rat when he notices the holes in the boys' story. Instead of arresting them based on that, he sets up a sting that confirms the boys' own guilt.
* Subverted in ''Series/VeronicaMars'': when a student accuses a popular teacher of sexual assault, Veronica quickly finds several contradictions in her story. Turns out the student actually was telling the truth except that she had changed the identity of the victim in order to protect her.

[[folder:Newspaper Comics]]
* ''ComicStrip/SlylockFox'' uses this trope in nearly every strip as Slylock's main way of crime solving.
** Parodied in [[http://www.gocomics.com/pearlsbeforeswine/2008/01/13 this]] ''ComicStrip/PearlsBeforeSwine'' comic.
** Blog/TheComicsCurmudgeon routinely speculates as to what kind of brutal police state the characters live in that allows Slylock to operate so capriciously and arrest people based on such flimsy cause (and in which he's sometimes shown not just as a detective but as [[KangarooCourt the prosecuting lawyer in court]]).
* Subverted on ''ComicStrip/CalvinAndHobbes'' when Susie is hit with a flurry of snowballs. She goes after Calvin, who has a wheelbarrow with him, and who protests that Susie only has "circumstantial evidence." She clobbers him anyway, and while lying face down in the snow Calvin claims that "you can't get a fair trial in this town."

* One episode of ''Radio/TheWhistler'' featured a man who killed his wife and made it look like a suicide. The police investigation and interrogation, conducted in the wife's apartment, has some close calls, but it looks like he's gotten away with it. The detective rises and heads for the door, ready to close the book on the case...and the wife's alarm clock goes off. Why would someone who's planning to commit suicide set their alarm clock to wake them up? The detective comes back, and says it's time to restart the interrogation from the top, as the husband breaks down.
* Parodied in ''Radio/JohnFinnemoresSouvenirProgramme'', in which the great detective John Finnemore deduces the maid is guilty of murder because she got a crossword clue wrong. "Impossible" is ''not'' a nine-letter word.

* A popular (well, often seen) riddle for kids goes like this: The detective is in a hotel room because the hotel's director told him that a famous thief is in the hotel. Then, someone knocks at the door of the detective's room. He opens, and there's a guy, who apologizes: "Sorry, I thought this was my room." The detective arrests him immediately, and guess what, it's really the GentlemanThief he was looking for. Oh, the reason? Because nobody will knock on the door of his own room—so the thief must've been checking whether the room was empty and he could plunder it! (Because it couldn't be, let's say, that his wife was in the room, had been taking a shower and he wanted to warn her, in case she wasn't dressed yet, and other people were in the corridor, or that he left the keys in the room while his wife stayed so he had to knock the doors. Guess the thief is at least guilty of not inventing a good excuse.)
* Another riddle involves the murder of a wealthy man who is killed on a Sunday. Upon being questioned, all of the servants give various alibis: "I was polishing the silver," "I was mowing the grass," etc. The "killer" is the one who claims to have been checking the mail, because mail isn't delivered on Sundays—because apparently, it's impossible to forget that and just check every day out of habit. Or to have forgotten to check on Saturday, and instead get the mail the next day. Or to receive a newspaper that is delivered on Sunday. Or to get mail delivered by others than the Postal Service (how uncommon this is may vary between countries).
** Especially erroneous in the US, since the USPS will deliver letters on Sunday for an extra charge.
* Yet another one had a woman who was attacked on the walkway leading up to her house, then the robbers tied her and her family up while robbing the place; the detective, arriving an hour later, noticed his long shadow in front of him on the same path and insisted that she was in on the robbery because she hadn't noticed her attacker's shadows behind her. Because it's not like the angle of the sun would have changed, or she simply hadn't noticed...
* One riddle involves having to figure out why a suspect was let go. It turns out he was deaf, and thus couldn't understand his {{Miranda rights}} when read to him. Aside from the fact that many deaf individuals know how to lip read, the whole idea hinges on {{Hollywood law}}, as no mention of him confessing is made. Obviously if he confessed the police would quickly have learned of his deafness and made sure his rights were understood, giving them in writing or through a sign language translator if necessary.

* In ''Theatre/TheCrucible'' by Arthur Miller, Sarah Osbourne is suspected of witchcraft because she muttered something after being refused alms when begging. She claims she was just reciting the Commandments, but she cannot recite them for the court and is thus convicted. This is in keeping with the overall point of the work, which is that the trials are inherently unfair and the 'evidence' is flimsy and being twisted by hysteria and malice.
* In ''Theatre/ThePajamaPartyMurders'', Pettibone's deduction of the murderer relies on contradictions with old secondhand information and things that only he has observed. Of course, they then admit to the crime and pull a gun.

[[folder:Video Games]]
* The first ''VideoGame/KnightsOfTheOldRepublic'' had a sidequest on Dantooine in which you determine which of two suspects is the murderer by poking holes in their testimonies. During the first round of questions, you find out that one of the two suspects lied, but he's not the murderer and it wouldn't do him justice to accuse him just based on this evidence—the truth is more complicated and can only be found out by repeatedly questioning both suspects and the forensic droid. You can also bypass the whole "logic" aspect and say that you know who did it and that your reasoning is that "[[Funny/KnightsOfTheOldRepublic fat people always lie.]]"
* ''VideoGame/MassEffect2'' has a sidequest where Shepard must use various fragments of messages to identify which of five possibilities is the [[KnowledgeBroker Shadow Broker's]] chief agent on Ilium. The solution comes down to the use of a single contradictory pronoun to give the answer [[spoiler:-'none of the above']]. Of course you are working for Liara, not the courts, and she's no longer too hung up on the whole 'reasonable doubt' thing.
** Of course, she also summons [[spoiler: Nyxeris to her office, where it is implied Nyxeris made the first move after being told she was guilty.]]
** This is actually an example where it probably would hold up in court, since it ''establishes'' reasonable doubt instead of trying to dispel it. The clue in question is that [[spoiler: the leader is female, and all the suspects are male. This means that the tip that forms the whole basis of the investigation is wrong and almost certainly a setup, ruining Liara's reputation as a knowledge broker by having her pursue the wrong target. Nyxeris is implicated because she was the source of the tip, not by the clue itself]].
* The DOS EdutainmentGame, ''VideoGame/EagleEyeMysteries'' falls victim to this at least once. Although the guilty party usually tells a very blatant lie that makes ''everything'' they say untrustworthy, you usually find other physical evidence too. Not so in one case, where a suspected Moon rock theft hinges almost entirely on the thief calling said object a sedimentary rock, despite the player researching in-game that it is physically impossible for a Moon rock to be sedimentary. No other evidence is found to implicate the suspect. (Because if you don't know your basic geology terms, you are clearly a thief.)
* ''VideoGame/InThe1stDegree'' plays with this trope. While the prosecutor is required to poke holes in Tobin's testimony in order to get first-degree murder, it could be argued that Granger achieved it because Tobin had a total meltdown right there in the courtroom and revealed to much information.
* Subverted in the Safe ending of ''VisualNovel/NineHoursNinePersonsNineDoors''. Junpei performs an epic set-up to reveal that [[spoiler:Ace has prosopagnosia and can't tell the difference between faces, and thus killed Snake.]] Ace points out that [[spoiler:his having prosopagnosia is true, but it in no way indicates that he was a murderer, and that he just kept it a secret because he was upset by it.]] Junpei agrees with this, and then says that the [[spoiler:prosopagnosia reveal]] was just a springboard to lead to evidence that ''did'' implicate [[spoiler:Ace in Snake's murder.]]
* In ''VideoGame/{{Contradiction}}'' this, along with PullTheThread, makes up the main interaction with the game. Notably, the player cannot use the testimonies of two separate people to contradict one, the other, or both. All lines of questioning are kept separate, and thus those questioned can only ever be called out as a liar for giving self-contradicting testimony. As such, the game does rather well at avoiding any one contradiction resolving the case, [[spoiler:with the closest the player character gets to jumping ahead of their evidence being threatening a full-scale investigation against a properly suspicious organization. Even the final contradiction doesn't completely nail the culprit down, with the reveal and arrest coming from an almost off-hand confession.]]
* ''VideoGame/KingdomOfLoathing'' has gotten into this trope as of 2016 with players taking the role of police detectives solving the day's latest in the series of "egg murders" taking place at mansions everywhere. Being unable to search for clues or evidence (although some of the ''suspects'' are doing so), or indeed take any action other than to wander the scene and interrogate suspects, this follows naturally. [[spoiler: However, it's an ''inversion'': most suspects are such pathological liars that if one both fingers a culprit and also correctly tells you even one verifiable fact about the scene or others you can make an arrest. Conviction By Non-Contradiction.]]

[[folder:Visual Novels]]
* Averted in the ''Franchise/AceAttorney'' series. The core mechanic of the game is to find and expose contradictions in witness testimony by presenting evidence. However, at no point is ''anyone'' ever proved guilty by a single contradiction alone. Instead, the objective is to expose a contradiction, which will then be covered up by a new, weaker story ("No! Wait! I was mistaken! It happened this way!") which can also be contradicted, [[PullTheThread and so on and so forth until the actual perpetrator's guilt is confirmed]]. The end result is that [[VisualNovel/PhoenixWrightAceAttorney Phoenix]], [[VisualNovel/ApolloJusticeAceAttorney Apollo]] and [[VisualNovel/PhoenixWrightAceAttorneyDualDestinies Athena]] always need to present a pretty extensive case and put forth quite a bit of evidence before the court even considers believing them. And even then, sometimes evidence will not be enough to convict a culprit, which sometimes requires getting a confession out of them (e.g. in Apollo's game, third case). Also, it's suggested that the real perpetrators have to undergo another trial at a later date, so even when Phoenix exposes evidence against them they aren't necessarily convicted immediately. Other times, though, pointing out the contradictions is actually perfectly valid when the point is to create doubt in the testimony of those accusing your client.
* ''VisualNovel/SuperDanganRonpa2'': The first solid clue that leads to the third culprit's identity is the fact that [[NeverSuicide their victim's cause of death was not by hanging, but rather by strangulation]]. [[spoiler:After all, how could Mikan, the Ultimate Nurse, have missed that when her autopsies had been so accurate before, unless ''she'' was the one trying to hide it.]]

* The TabletopGame/PerplexCity card "Alibi" pegs [[spoiler:the maid]] as a murderer because she said she was getting the mail at the time of the crime—a Sunday. (Of course, no one ever picks up Saturday's mail on Sunday.)
* Parodied in an article from Website/TheOnion about [[http://www.theonion.com/content/node/29537 the boy detective's murder]]. Bugs claims that "at the time the crime was committed, I was at [[PolarBearsAndPenguins the North Pole watching the penguins]]".

[[folder:Western Animation]]
* Parodied in ''WesternAnimation/MoralOrel'', in which Orel starts a detective agency. There are two suspects when the contents of Reverend Putty's collection basket is stolen: Joe the DevilInPlainSight, and a clearly-innocent Susie. Orel ignores the expensive ice cream Joe has bought, and the fact Susie wasn't even in church at the time, and bases his conclusions on which Commandments they broke (or didn't break): Joe honored the Commandment about keeping the Sabbath Holy by refusing to cut his grandfather's lawn, while Susie broke the Commandment of honoring her parents by volunteering at a retirement center instead of going to church like she was told. If she broke one Commandment, then [[JumpingOffTheSlipperySlope surely she would be the sort of person to break "Thou shalt not steal".]]
* DoubleSubversion in ''WesternAnimation/BeavisAndButtHead'', of all shows. When our heroes are accused of egging Tom Anderson's house, Butt-Head is inspired by a court reporter he saw on TV to try and discredit Anderson's testimony by pointing out that Anderson couldn't clearly identify who threw the rotten eggs at his house. The judge is about to dismiss the case when the prosecutor objects, stating that neither Anderson nor any of the police reports or court documents [[INeverSaidItWasPoison had ever said the eggs were rotten]]. He then asks how Butt-Head could have known the eggs were rotten unless he and Beavis were the ones that threw them. Butt-Head has no response, and he and Beavis are sentenced to 500 hours of community service.
* ''WesternAnimation/{{Rugrats}}'' had an episode like this titled "The Trial." After Tommy's favorite clown lamp is broken, Angelica suggests that he [[ExactlyWhatItSaysOnTheTin hold a trial]] to determine the culprit. Angelica plays the role of "persecutor" and attempts to finger Phil, Lil and Chuckie as the "poopatrator", pointing out their various actions that endangered the lamp, but they're able to defend themselves. It isn't until Tommy realizes that [[spoiler: Angelica's supposed "alibi"--she was taking a nap---doesn't hold up because she supposedly took one earlier at her own house (the episode opens with her coming into the room after "waking up," but she's clearly lying)]] that the babies realize that it would have been impossible for her to know what exactly they were doing and thinking unless ''she was there'', which she was.
* In "[[Recap/TheSimpsonsS1E12KrustyGetsBusted Krusty Gets Busted]]", the first Sideshow Bob episode of ''WesternAnimation/TheSimpsons'', Bart and Lisa's investigation basically comes down to this. First Lisa realises that Krusty wouldn't have used the Kwik-E-Mart microwave because he has a pacemaker, then that he couldn't have been reading the Springfield Review of Books at the magazine rack because he can't read. When Bart brings these points up on Sideshow Bob's show, Bob argued that Krusty wasn't one to follow medical warnings, and didn't need to be able to read to enjoy the Springfield Review of Books, thanks to the cartoons. Finally, in a EurekaMoment, Bart remembers that Homer stepped on the ends of fake Krusty's long shoes, causing him to exclaim in pain. Although Krusty usually wears oversized shoes, his feet don't fill them, so he wouldn't have felt a thing; Sideshow Bob, however, has feet long enough to fill the shoes.
** Parodied in a random Duff poster that appears on an episode where Homer and Barney visited the local plant, which (having been done during The UsefulNotes/ColdWar) had someone ''[[DisproportionateRetribution accused of being a Communist spy and arrested]]'' simply because he didn't liked Duff.
* An episode of ''WesternAnimation/TheRaccoons'' titled "Simon Says" involves an aardvark claiming to be Cyril Sneer's long lost brother, Simon, who wants his share of the Sneer fortune. Simon claims to have been trapped on a desert island for a long time and eventually built a boat to get himself off the island. Bert however is suspicious and spends the episode trying to expose Simon as a fraud. [[spoiler: Bert succeeds and when asked what made him wary, it's explained that during their initial handshake, Bert noticed Simon's hands were very smooth. If he had worked on building his own boat, his hands should have been rough and callused.]]
* Zigzagged in "False Alarm," an episode of ''WesternAnimation/HeyArnold''. Eugene is accused of pulling a fire alarm, and a jury of students--consisting of Arnold, Gerald, Phoebe, Helga, Harold, and Curly--is called to find him guilty. Arnold is the lone holdout (much of the episode parodies ''Film/TwelveAngryMen''), and eventually uses this trope to prove his point: one of the pieces of evidence is a pencil from Wankyland, an amusement park, found near the broom closet where Eugene was discovered hiding. Arnold argues that Eugene ''couldn't'' own a Wankyland pencil, as he was banned from the park for [[NoodleIncident somehow ruining a Thanksgiving Day parade]] the previous year. It's never suggested that Eugene might have had the pencil from ''before'' being banned, but it turns out to be a moot point, as the real culprit--Curly--reveals himself once Arnold makes this argument.

[[folder:Real Life]]
* Explicitly averted in Canadian jurisprudence. A famous Supreme Court decision, ''[[http://www.canlii.org/en/ca/scc/doc/1991/1991canlii93/1991canlii93.html R. v. W. (D).]]'', established that trials are never mere credibility contests between the Crown (prosecution) and defence, and that it is not sufficient to disprove the defence's story, but the Crown must itself prove its version of events beyond a reasonable doubt. The ruling introduced an oft-quoted way to explain this:
-->First, if you believe the evidence of the accused, obviously you must acquit.
-->Second, if you do not believe the testimony of the accused but you are left in reasonable doubt by it, you must acquit.
-->Third, even if you are not left in doubt by the evidence of the accused, you must ask yourself whether, on the basis of the evidence which you do accept, you are convinced beyond a reasonable doubt by that evidence of the guilt of the accused.
* This is one of the reasons you're never supposed to talk to police officers unless there's a lawyer present. It's quite easy to say something that could be misconstrued as suspicious or incriminating, and police in RealLife are more diligent than in fiction about using holes in a person's statement as a starting point to single out the suspect(s) who will be investigated more thoroughly via obtaining warrants and gather the real evidence that's used in a conviction. When the police tell you [[MirandaRights anything you say "can and will" be used against you]], they aren't kidding. Conventional legal wisdom is to invoke your right to an attorney and [[http://www.youtube.com/watch?v=i8z7NC5sgik never speak]] [[http://www.youtube.com/watch?v=08fZQWjDVKE to police officers]] if you think the police suspect you of a crime. The lawyer is there as a witness.
* Police are also more experienced and versed at some of the less well-known cues for discerning between how an innocent person vs. a guilty one will react to being accused of a misdeed and what would constitute suspicious behavior/language:
** An innocent person accused will deny it, while a guilty person might make a statement that doesn't depend on actual innocence, such as "You can't prove that!" As pointing out that the accusation is by contradiction rather than evidence is closer to the second reaction than the first, it's not unreasonable for [[LampshadeHanging lampshading]] this trope to trigger a (further) investigation.
** However, trying to tell truth or falsehood by someone's behaviors like this is questionably useful at best. [[http://psycnet.apa.org/psycinfo/1989-13781-001 One study]] suggested that training to detect these sort of details did not increase accuracy in detecting truth or falsehood, and in fact the longer a cop did his job the ''worse'' he became at determining truth from falsehood. This has led to [[http://www.salon.com/2012/09/16/can_we_detect_when_someones_lying/ people ending up in jail]] due to not being shocked enough, or too shocked, about a death. The reason behind this is simple: when you focus too much on ''behavior'' to tell if someone is lying, you stop focusing on the best way to tell—their story simply doesn't add up.
* Also, the "found out as a foreign spy because—" examples are very much TruthInTelevision if for no other reason than if you're found out as a spy, you're less likely to end up in front of a jury in a public court with all those pesky "standards of proof" and more likely to end up in a dark hole in a location known to no one with the government of the host country giving you some [[JackBauerInterrogationTechnique harsh interrogation]], and pointing out the holes in their evidence is most certainly going to fall on deaf ears.
** Though obviously easy to take too far, espionage is at least as much a national-defense issue as a criminal issue, and the primary purpose of interrogating spies is not getting a conviction, it's finding out A) what they've found out and B) how many other spies are in your country, and if possible, who they are.
** For that matter, in the "found out as a spy/impostor" cases, there would usually be plenty of other evidence about the person having engaged in espionage/not being who or what they claim to be; the contradiction is simply the first thing to alarm the officials to perform a more thorough investigation, which turns up the actually incriminating evidence. They're not strictly speaking ''convicted'' by contradiction, but when their entire plan depended on not having anyone find out what they're up to, getting attention cast on them because of that contradiction is just as bad.
* One of the Al-Qaeda bombers who attacked the US Embassy in Nairobi was rumbled this way. He was supposed to have committed suicide after his task (to throw a sound grenade into the courtyard to draw people to the windows before the bomb hit) was complete, but [[BlatantLies suddenly found a very good reason not to]], and fled to a hotel in the suburbs. When the Agency interviewed him, he told them that he was wearing the same clothes he had worn on the day of the explosion. But they were pristine, whilst the CIA agents' clothes were worn after only a few days in the country. Then, he claimed he washed them. Not impossible. However, his belt, which he claimed to have been wearing on the day of the blast, was pristine, as opposed to the worn straps Kenya had made of the CIA's. And you don't wash a belt, so it must have been put on later, so the man must have been lying. When this error was pointed out to him, he spilled all.
* [[http://en.wikipedia.org/wiki/Shibboleth Shibboleth]]: A word or custom specific to a particular group or subculture that most outsiders incorrectly identify or pronounce. Getting the name or tense of a local slang, street or landmark can identify someone as a foreigner at best (see the myriad differences in the ways Americans vs. Canadians pronounce words like ''about'') and a German spy at worst (see the Isaac Asimov short story with the Star Spangled Banner). Shibboleths were used in history during ethnic and cultural conflicts as tests to distinguish an outsider trying to conceal themselves and the penalty was typically execution on the spot, as in the [[TropeNamers Word Origin]], the biblical story in the Book of Judges of the execution of Ephraimite refugees who mispronounced "Shibboleth" as "Sibboleth". [[Wiki/{{Wikipedia}} That Other Wiki]] has a full breakdown of the [[http://en.wikipedia.org/wiki/Comparison_of_American_and_British_English subtle differences in American and British English]] that are possible Shibboleths in everyday conversation.
* A public defender recalled a story on ''The Moth Radio Hour'', in which he was defending a man accused of smashing a window with a paint can by throwing it in from outside. It was an incredibly minor charge, and the prosecutor was willing to drop it if the defendant would just pay for the cost of replacing the window. However, the defendant swore up and down that he hadn't smashed the window (for extra salience, there was apparently a woman involved, that both the defendant and the window's owner were having sex with), and wanted to go to trial. During pre-trial prep, the public defender noticed that the prosecutor wasn't going to call the police officer that responded to the original complaint, which struck him as odd. He, however, ''had'' spoken to the police officer, and he therefore knew that he was going to win the case. He called the officer to the stand (which is extremely rare, for a cop to be called as a witness for the ''defense''), and asked if the owner of the window had allowed the officer into the room with the smashed window. Well, no, replied the officer. Alright, did you get to see the paint can? Well, no, replied the officer. Did you get to see the shattered window? Yes, the officer replied, but only from outside. And where was the broken glass? Well, replied the officer, it was on the ''outside'' of the window...