History Main / ConvictionByCounterfactualClue

** One episode has Cate determining a suspect is lying because he looks to his left, so he's obviously recalling a concocted story. Had he been telling the truth, he would have looked to the right.

** In another episode Catherine (again) catches a woman who killed her daughter by which way the woman was looking when she was talking to Catherine. Catherine deduces that the woman was looking left and therefore lying. To be fair, she only brought it up after using a forensic demonstration to learn that no-one ''but'' her could've drowned her daughter, but it seems very weird that she'd use eye direction as evidence after that.

** This happened with Encyclopedia Brown himself. Bugs Meany lied by copying another kid's true version of events, changing washer to dryer but otherwise using the exact same words. The first kid said he'd put the clothes in from the top, and Bugs copied that detail.

* One entry in ''Literature/TheArmchairDetective'' series stated that one true way of knowing if a pre-UsefulNotes/WorldWarII telegram is false is if the phrase "UsefulNotes/WorldWarI" or "The First World War" is ever mentioned, on the assumption that nobody could have foreseen a second World War before it started. However, [[http://en.wikipedia.org/wiki/World_War_One#Names it was used by some almost immediately after hostilities began.]] Note that the series in general isn't particularly prone to this. In his defense, those were not ''common'' terms, and would hardly be included in a telegram where they could easily say "The War" or "The Great War" with fewer letters. It may not be rock-solid evidence, but it's a good reason to be very skeptical.
** It should be noted that using them as the actual ''name'' of the War would be even more suspicious—although the First World War was, indeed, used, it at first was more of a descriptive term (IE, describing the War as the first World War in contrast to previous, non-global, wars, and, as in the case of the first recorded use of the term, the early-war term 'The European War').

** In "The Adventure of the Priory School", Holmes deduces the direction a bicycle was heading by the fact that the hind tire track passes over the front tire track. However, the hind tire would pass over the front tire tracks regardless of the direction (unless the bicycle was in the process of turning at the time). [[https://mindyourdecisions.com/blog/2010/02/02/a-mystery-sherlock-holmes-couldnt-solve-but-you-can/ This article]] explains an actual way of figuring out the bicycle's direction.
*** Conan Doyle himself checked that theory after getting some mail from the readers, and admitted that this is, indeed, his mistake; he also said that Holmes could've used a different clue: on an uneven ground the bike leaves a deeper track when going upwards than downwards, and that is enough in the context of the story.

** Book 12, chapter 5 ("The Case of the Mysterious Thief"): The case was "solved" (by Sally, not Encyclopedia) because a couple sat in a restaurant with the man's back to the wall rather than the woman's, from which Sally deduced that each was actually a member of the other gender in disguise. This is because of a rule of etiquette that the woman should sit against the wall, so she can see and be seen. For this to be evidence, it would have to be the case that people followed this "rule" with no, or at best, very few exceptions; only Sally had ever heard of it. This same solution supposes that the victim is a woman so strong only a man could've knocked her out with one punch, ignoring the fact that the victim is, well, a very strong woman, which by itself admits that very strong women exist.
*** From a meta perspective this "solution" also ignores what a big piece of the books' internal logic "girls can be even tougher than boys" really is. The canonical reason the bullies Encyclopedia outsmarts don't try to get even by just punching his teeth out is his partnership with Sally, who beats up anyone who tries. The books go so far as to actually call her his bodyguard whenever they explain this.

** Book 2, chapter 8 ("The Case of Excalibur"): Supplies the page quote, in which one kid with a cast on his left arm is accused of stealing a penknife, and in fact it's found in his pants pocket in his locker. However, the "proof" that he didn't do it is found in that the knife is in his left pocket, and, according to Encyclopedia, it's ''impossible'' to put something in the opposite pocket of the hand they're in while running, as Bugs Meany claims happened. It might be more difficult for some than others, and there would be very little logical reason to do so, but it's certainly not impossible for ''everyone''. Though in a technical subversion of this trope, the pants pocket scene isn't actually the final ''conviction'' per se.

* The trope is {{invoked}} and [[LampshadeHanging lampshaded]] in ''ComicBook/WelcomeToTranquility''. Emoticon is in jail and being questioned with regards to the murder of Mr. Articulate, a crime-solving member of the community who was legendary for his intellect, wit and long and storied history of traveling the world. However, Emoticon points out that a lot of the stories of his adventures were "[[ValuesDissonance culturally insensitive]]", and he recounts one of the detective stories from Mr. Articulate's youth that always stuck in his mind: Mr. Articulate discovered the identity of the murderer because the "Korean" man at dinner left his chopsticks in his bowl of rice, something no actual Korean would do since it is a symbol for death and, therefore, he must not be Korean, but Japanese instead, and thusly the killer. However, Japanese culture has ''the same custom''. "So the ending doesn't ''work''. It's a ''cheat''."
** Of course, Koreans eat rice with a spoon, so there's one more reason it doesn't work. They eat other dishes with chopsticks.

** "A Study in Pink" has Sherlock deduce that the former owner of John's mobile was his brother and a drunk runs entirely on these. He assumes that people not wanting to pay the entire rent of a flat would be frugal in every other aspect of their lives despite flat mates being quite common among people of varying financial backgrounds. He assumes that older people don't have cell phones, which was sort of true in the time period when the show was made but the phone being a gift explains that. The scratches on the power connection are a shout out to the same deduction being used in the original stories but for watch winding. However as most cell phone owners can attest, the tiny plug of that style of cell phone is difficult to find and people often plug their phones in in the dark, most cell phones over six months old will have scratches around the outlet, whatever the owner's intoxication level. In fairness, he did admit the last one was a "shot in the dark," and later explicitly stated he wasn't expecting to get ''everything'' right (again, as in the book).

* ''Series/DoctorWho'': [[Recap/DoctorWhoS31E12ThePandoricaOpens "The Pandorica Opens"]] has an in-universe example: The [[LegionOfDoom Alliance]] believes the Doctor to be responsible for the impending reality-ending catastrophe caused by [[spoiler:the TARDIS exploding]] because "only the Doctor can [[spoiler:pilot the TARDIS]]". Not only does the audience know this is not the cause, the episode makes sure to remind people that this logic is faulty by showing [[spoiler:River Song flying the TARDIS after the Doctor sends her to go get it]].

** In a first-season episode, Jessica solves a murder by realizing that the police Lieutenant who was investigating the murder dismissed a spot where a framed item had been removed as having been nothing more than a family picture could only have known that if he had been inside the home prior to being summoned, as the victim's daughter had removed the picture as soon as she found her father dead. Except that he could have potentially learned that from the various people who were in the house when the body was discovered. This is a bit downplayed, though, as the Lieutenant does not think to offer this excuse and instead pulls a gun -- the murder weapon -- on Jessica, who (after he is disarmed) acknowledges is the only real piece of evidence.

** One episode has Cate determining a suspect is lying by the same logic. He looks to his left, so he's obviously recalling a concocted story. Had he been telling the truth, he would have looked to the right.

** Book 1, chapter 3 ("The Case of the Civil War Sword"): Bugs Meany claims to have a sword from UsefulNotes/TheAmericanCivilWar, and says it's authentic due to the engraving showing that it was given to Stonewall Jackson by Robert E. Lee after the First Battle of Bull Run. The 'correct' answer was that the sword was fake, because [[AnachronisticClue nobody would have called it FIRST Bull Run]] until there had been a Second Bull Run (and the sword was dated August 21, 1861, just a month after the first battle -- although given how long it can take to commission, make, retrieve, and engrave a sword, it's entirely possible that the second battle a year later already happened by the time the sword was actually finished), and that Confederate forces did not refer to either battle as Bull Run at all, but rather as the Battles of Manassas[[note]]The one being Union-specific nomenclature referring to a creek that passes through the battlefield, the other being Confederate nomenclature referring to the nearby city of Manassas, VA[[/note]]. However, there's an even bigger hole in the story: General Lee wasn't ''present'' for the First Battle of Bull Run/Manassas: the Confederates there were led by P.G.T. Beauregard. (Sobol edited the epilogue in later editions to include this fact.)

* In the Creator/MaryHigginsClark novel ''While My Pretty One Sleeps'', the as-yet unidentified killer notes that he made a major error in dressing his victim's body and realizes that the protagonist will realize it, given her knowledge of fashion (she's a designer and designed the outfit that the woman is dressed in, but he got the shoes wrong, a mistake that the victim, herself a designer, wouldn't have made.)

* In a ''Literature/MikeMistMinuteMystery'' by Max Allan Collins in the early 1980s, the title character supposedly identifies a crook because she claimed that she cashed a check using an automatic teller machine, which Mike claims is impossible. The readers wrote in to note that it's done ''all the time''; you enter the value of the check into the machine as a deposit and you are free to withdraw from that amount, with the bank staff confirming the accuracy and legitimacy later on; in modern days the ATMs are smart enough they even handle the verification process.

** The page quote comes from a mystery where one kid with a cast on his left arm is accused of stealing some keys, and in fact they're found in his pants pocket in his locker. However, the "proof" that he didn't do it is found in that the keys are in his left pocket, and, according to Encyclopedia, it's ''impossible'' to put keys in the opposite pocket of the hand they're in while running, as Bugs Meany claims happened. It might be more difficult for some than others, and there would be very little logical reason to do so, but it's certainly not impossible for ''everyone''. Though in a technical subversion of this trope, the pants pocket scene isn't actually the final ''conviction'' per se.
** In one case, the culprit's alibi was that, when he walked past the victim's house, he heard the electric clock (which was unplugged when the crime was committed) ticking, the contradiction being that electric clocks don't tick. When this was first written, (back in the 1970s), this was ConvictionByContradiction, though questions like "How loud would it have to be ticking to be audible outside the house?" and "Exactly how is this an alibi anyway?" might arise. Today, we can skip straight to the fact that some electric clocks -- particularly analog clocks in which the second hand jumps from one mark to another and an early kind of digital clock where numbers were written on flaps that showed in succession (as shown in ''Film/GroundhogDay'' among others) -- ''do'' make sounds that, while distinct from pendulum-regulated clocks, are described as ''"ticking"''. Additionally, some digital clocks that indicate seconds will play an artificial ticking sound.
*** One of the Inspector Berkovich stories[[note]]a collection of short stories for Israeli Russian speakers, with many of the stories being expansions of the Two-Minute Mysteries[[/note]] has a witness claim he saw a man being murdered while a clock was ticking - except it was digital. The twist is; the man was completely honest; he was hearing a particular radio station which always transmitted a metronome's ticking for a few minutes before its regular broadcasts started.
** One involving a sword from UsefulNotes/TheAmericanCivilWar. The guy hawking it claimed it was authentic due to the engraving showing that it was given to Stonewall Jackson by Robert E. Lee after the First Battle of Bull Run. The 'correct' answer was that the sword was fake, because [[AnachronisticClue nobody would have called it FIRST Bull Run]] until there had been a Second Bull Run (and the sword was dated August 21, 1861, just a month after the first battle -- although given how long it can take to commission, make, retrieve, and engrave a sword, it's entirely possible that the second battle a year later already happened by the time the sword was actually finished), and that Confederate forces did not refer to either battle as Bull Run at all, but rather as the Battles of Manassas[[note]]The one being Union-specific nomenclature referring to a creek that passes through the battlefield, the other being Confederate nomenclature referring to the nearby city of Manassas, VA[[/note]]. However, there's an even bigger hole in the story: General Lee wasn't ''present'' for the First Battle of Bull Run/Manassas: the Confederates there were led by P.G.T. Beauregard. (Sobol edited the epilogue in later editions to include this fact.)
** Encyclopedia Brown pinned a crime on a magician because he was wearing short sleeves. He claimed that all magicians wore long sleeves so that they could pull objects out of them... except good magicians don't need anything of the sort. Many, in fact, wear short sleeves solely to impress people with the undeniable fact they have nothing up them, and at least one group [[{{Fanservice}} performs magic in the nude]]. There are entire styles of magic that depend on (for example) marked cards, psychological tricks, or props with trap doors, for which sleeves are completely useless. Even in cartoons, stage magicians as a whole tend to have the catchphrase "nothing up my sleeves", as they roll them up before a trick.
** One case was "solved" (by Sally, not Encyclopedia) because a couple sat in a restaurant with the man's back to the wall rather than the woman's, from which Sally deduced that each was actually a member of the other gender in disguise. This is because of a rule of etiquette that the woman should sit against the wall, so she can see and be seen. For this to be evidence, it would have to be the case that people followed this "rule" with no, or at best, very few exceptions; only Sally had ever heard of it. This same solution supposes that the victim is a woman so strong only a man could've knocked her out with one punch, ignoring the fact that the victim is, well, a very strong woman, which by itself admits that very strong women exist.

** Another solution was based entirely on the supposed 'fact' that roosters ''only crow when they saw light'', apparently based on the urban legend that roosters crow at sunrise. The crime was a con man trying to convince kids he found a way to make roosters crow on command, but actually uncovering the cage so they saw light and thought it was sunrise; he claimed that he would soon improve the device to make hens cluck on command, and that whenever hens clucked, they laid an egg. Anybody who has been around a rooster for an extended period of time will know full well that they crow whenever the heck they want, whether the sun is out or not. And, of course, the hen part of his story should have been clearly false, especially since he was targeting the con towards chicken farmers.
** One solution in "Encyclopedia Brown Sets the Pace" relied on the fact that the culprit had used glycerin tears that fell from the outside corners of her eyes instead of the inside, thus revealing them to be fake, as "If only one tear falls, it will run from the inside corner of the eye, by the nose, and not from the outside corner." Only, none of that is true; how tears flow from a person's eyes is a function of the physical shape of their eyelids, nose and cheek, not to mention the orientation of the head relative to gravity's pull.
** In Encyclopedia Brown and similar riddles there are puzzles about coins being a forgery because the name of the ruler is King Bob the First or similar. Obviously, no monarch referred to himself as The First, right? Except that they did—either to show that they're first among equals, or because they had a son named after them, or because they would indeed be the first monarch with that name, as was, for instance UsefulNotes/ThePope John Paul the First. Or recently abdicated Juan Carlos I (John Charles the First) of Spain.
** In the first case, Encyclopedia Brown deduces that the blind witness is lying because he has a newspaper in his room. Ignoring all the reasons one might have a newspaper one can't read in one's room[[note]]Perhaps the hotel hands out complimentary newspapers; maybe he was using it to wrap something, or he bought something that came wrapped in the newspaper; maybe he was going to do a messy project and needed a disposable surface[[/note]], it isn't even necessarily true that blind people can't read newspapers. Most legally "blind" people still have some amount of vision, and depending on the exact nature of the vision loss, it's entirely possible to be able to read a newspaper (perhaps with magnification).
** In one case involving a ShowWithinAShow, the solution to the crime lay in the fact that the murderer didn't leave prints, and "it was too hot for gloves," so they arrested the guy in gloves. Plenty of people wear gloves for all kind of reasons and in all kinds of weather.

** In one of the Two-Minute Mysteries, a man's death is taken not to be suicide because he had recently suffered a heart attack, so a salt shaker on his table would mean another person was present, since the man himself would not be adding any to his food. A man intending to take his life could easily have ignored health concerns.

* Mostly Averted in real life investigations and criminal proceedings due to detectives, judges and lawyers knowing better. However, this trope is very common in [[ConvictedbyPublicOpinion the court of Public Opinion]], mostly as a result of DoubleStandard, stereotypes, bias for/against a particular group and/or ignorance.

** One involving a sword from UsefulNotes/TheAmericanCivilWar. The guy hawking it claimed it was authentic due to the engraving showing that it was given to Stonewall Jackson by Robert E. Lee after the First Battle of Bull Run. The 'correct' answer was that the sword was fake, because [[AnachronisticClue nobody would have called it FIRST Bull Run]] until there had been a Second Bull Run (and the sword was dated August 21, 1861, just a month after the first battle). However, given how long it can take to commission, make, retrieve, and engrave a sword, it's entirely possible that the second battle a year later either already happened or was soon coming, necessitating the need for specificity. In fact, there are two other problems with the story, both of which would have been better pieces of evidence. One, Confederate forces did not refer to either battle as Bull Run at all, but rather as the Battles of Manassas,[[note]]The one being Union-specific nomenclature referring to a creek that passes through the battlefield, the other being Confederate nomenclature referring to the nearby city of Manassas, VA. Incidentally, the solution to the mystery does point this bit out too.[[/note]] and two, General Lee wasn't ''present'' for the First Battle of Bull Run/Manassas: the Confederates there were led by P.G.T. Beauregard. Sobol pointed this latter fact out in later editions.

[[quoteright:350:[[ComicBook/JimmyOlsen https://static.tvtropes.org/pmwiki/pub/images/bowtie_3.jpg]]]]

* One ''ComicBook/JimmyOlsen'' comic featured Jimmy [[WholesomeCrossdresser crossdressing]] to [[ItMakesJustAsMuchSenseInContext test the detective skills of his fanclub]]. They found him out in part because "Jackie" had tied a bowtie into a garter, to show "herself" as a member of the club, and according to them, "girls don't wear neckties and never have the practice to tie them ''that'' well." This is probably news to the millions of women who help their boyfriends, sons, or husbands with getting their ties on.

** Another amusing in-universe example in ''Series/StarTrekTheNextGeneration''. At the beginning of the episode "Ship in a Bottle", Data, playing Sherlock Holmes on the holodeck, says that the suspect has to be guilty because the attacker was left handed. Data throws an object at the suspect, which the suspect catches, proving that the suspect is left handed. Except, as Geordi points out, the object is in the suspect's RIGHT hand. Data notes that there must be a glitch in the holodeck switching the dominant hand of the holodeck characters. [[AGlitchInTheMatrix This actually becomes a critical clue later in the episode.]]

* ''Manga/CaseClosed'': The Moonlight Sonata case uses the belief that [[ValuesDissonance all women are physically weaker than all men]], as a foolproof alibi. Even when there's an elderly, overweight or disabled man in the room who doesn't get the same courtesy. A female doctor is written off as a suspect because she's petite with thin arms and couldn't have lifted the bodies. (Each of which are taller than her and would require quite a feat to move around the way they did.) Then [[spoiler:when it's found out "she" is actually a crossdressing man this alibi immediately vanishes, ''even though he's still the exact same muscleless {{Bishounen}} waif.'']]

* ''Manga/DetectiveConan'': The Moonlight Sonata case uses the belief that [[ValuesDissonance all women are physically weaker than all men]], as a foolproof alibi. Even when there's an elderly, overweight or disabled man in the room who doesn't get the same courtesy. A female doctor is written off as a suspect because she's petite with thin arms and couldn't have lifted the bodies. (Each of which are taller than her and would require quite a feat to move around the way they did.) Then [[spoiler:when it's found out "she" is actually a crossdressing man this alibi immediately vanishes, ''even though he's still the exact same muscleless {{Bishounen}} waif.'']]

** In one of the Two-Minute Mysteries, a man's death is taken not to be suicide because he had recently suffered a heart attack, so a salt shaker on his table would mean another person was present, since the man itself would not be adding any to his food. A man intending to take his life could easily have ignored health concerns.

** In the first case, Encyclopedia Brown deduces that the blind witness is lying because he has a newspaper in his room. Ignoring all the reasons one might have a newspaper one can't read in one's room[[note]]Perhaps the hotel leaves the local newspaper in every room[[/note]], it isn't even necessarily true that blind people can't read newspapers. Most legally "blind" people still have some amount of vision, and depending on the exact nature of the vision loss, it's entirely possible to be able to read a newspaper (perhaps with magnification). Not to mention that someone might have a use for a newspaper that ''doesn't'' involve reading the thing, e.g. wrapping something in it.

* ''Series/UnsolvedMysteries'': A segment featured a missing woman whose husband claimed that she had walked out on him, citing that several of her things and her suitcase were missing. When her suitcase was found, it contained ''exactly'' what he said it would, peaking the cops' suspicions, as they found it highly unlikely that any man could know exactly what was in his wife's suitcase, as he himself had no idea what was in his own wife's purse. (It's actually a very sad aversion, as to this day, the woman remains missing, and despite the cops' strong suspicions that he killed her, they have zero evidence to support this, meaning he remains a free man.)

** Reid insists that a person who kidnapped a child and then makes threatening phone calls to his parents utilizing a voice changer is in fact a woman, because the caller didn't taunt the FBI, therefore the kidnapper isn't competitive and ego-driven, and because they insisted on describing certain aspects of the child's clothing, such as his shoes being teal, the idea (which Reid actually spells out) being women wouldn't be competitive and ego-driven, and only women notice or call attention to small details like colors. He turns out to be completely right on all points as regards the perpetrator, which, of course, ignores the alternate possible explanation that people are individuals and plenty of men are not competitive by nature and notice small things like shoe colors. The kidnapper having been a shoe salesman might've been an interesting reveal.

** In the short story "The Warrior", Harry saves a girl from being hit by a car. When her mother comes to see what happened, Harry spots a bruise on the girl and asks if he gave it to her when he pulled her out of the car's path. The girl says no, she was bruised when she fell off her bike. Harry then asks how that happened without her scraping her hands. The mother's eyes go wide with realization and she promptly marches the girl home. Later Harry learns that her father had been hitting her, and Harry's comment brought it to the mother's attention. Of course the girl could have easily fallen off a bike without scraping her hands. While the mother may have known or suspected what was going on, there was no real reason for Harry to think it was a particularly suspicious claim.