Two or more groups have an agreed-upon set of rules, contracts, oaths, or other agreements. But when one side violates these, the other side may well declare those rules null and void, and thus freely disregard and violate them as well.
Contrast Honor Before Reason (where one side may adhere to rules while the other breaks them left and rightnote ). At the other extreme, an unscrupulous party may accuse the other side of breaking some minor technicality and use it to weasel out of their part of the deal.
See also Hostage for MacGuffin, where this trope is the main cause of the heroes getting out of the exchange with both.
Do Unto Others Before They Do Unto Us is a related trope, where a party justifies amoral actions (which may or may not violate some sort of law or agreement) by claiming someone would inevitably do it.
- The Monster World arc of Yu-Gi-Oh! has Dark Yugi respond to Dark Bakura using tricks to improve his dice results by copying him. He simply notes in response, "If you can cheat, I can too." Bakura responds by creating an Obvious Rule Patch to prevent either of them from using the trick, to which Yugi agrees. (Granted, Bakura has multiple other ways to cheat that Yugi can't copy, such as placing a piece of his soul into the dice.)
- In Yu-Gi-Oh! 5D's, Yusei duels against the corrupt warden, Takasu, who basically cheats in his duel against Yusei by having his men look at the cards in Yusei's hand with the security cameras. So when Yusei's cellmate Alex causes a power outage, Yusei takes advantage of the blackout to switch the position of his face-down cards to trick Takasu into targeting the wrong card.
- In The Death of Clark Kent, Superman and Conduit agree to fight with Supes not using his heat vision and Conduit not using his Kryptonite rays. When Conduit breaks the rules, Superman follows suit.
- Wacky Races: In "The Speedy Arkansas Travelers" (issue #5, Gold Key) Dick Dastardly employs chewed bubble gum to halt the progress of the Army Surplus Special. But when the Arkansas Chuggabug's Luke and Blubber gets the Mean Machine hung up the same way, Dastardly complains vehemently.
Dastardly: No fair! They did my dirty trick! To me! I'll sue!
- A Running Gag in the X-Men Baseball Episodes is that the game starts off being "no powers", but as soon as one player violates this...
- Ashikabi Of Thunder And Lightning: Tsukiumi tries to attack Minato the first time they meet, leading to both of Minato's present Sekirei attacking her. When Tsukiumi insists that matches are supposed to be one on one, they remind her that attacking an Ashikabi is also forbidden.
- In Holiday Inn early in the film Ted "steals" Lila from Jim. Lila leaves Ted for another man, and Ted shows up at the Inn in horrible shape. He falls in love with Linda, who Jim is in love with, and manages to talk her into going to Hollywood with him. Jim's housekeeper encourages him to go to California (where Ted & Linda are busy making a movie based on the in-universe Holiday Inn) and get her back. Jim says "A fella doesn't steal another fella's gal. ...Or come to think of it, does he?"
- On the first possession of the Ultimate Game in Space Jam, Bugs Bunny starts dribbling the ball upcourt until Pound smacks him hard enough to send the rabbit skidding the width of the court. No foul is called, and Michael Jordan gives a "woof" at just how rough the game is going to be. The Monstars continue to play nasty while the Tunesquad plays nice, until the second half. Then the Looney Tunes bring in explosives and firearms and livestock, which begins to even the score. No foul of any kind is called, ever.
- Conman Henry Gondorff joins banker Doyle Lonnegan's crooked poker game in The Sting in order to earn Lonnegan's ire. Once Gondorff is dealt a hand of four Treys, he knows a stacked deck play is in effect. At the climax of the hand, Lonnegan plays four Nines ... and Gondorff lays down four Jacks. When his adjutant wonders why Lonnegan suffered the loss, Lonnegan growls at him: "What was I supposed to do? Call him for cheating better than me in front of the others?"
- Constantine. Papa Midnite has sworn an oath to uphold the Balance between Heaven and Hell. In an attempt to convince him to go back on his oath and intervene in the conflict, Constantine tells him that the forces of Hell have broken the rules and violated the Balance.
- Cloud City administrator Lando Calrissian from The Empire Strikes Back played along with The Empire, allowing them to set a trap for young Skywalker. Lando had qualms about torturing Han Solo, then handing him over to a bounty hunter, but he was cowed by Darth Vader. However, after being ordered to take Princess Leia and Chewbacca to Vader's shuttle, Lando protested, and was met with Vader's "I am altering the deal; pray I don't alter it any further." No surprise that Calrissian gets on the PA system, alerts the city that The Empire has seized control, and actively joins the rebellion.
- Fist of Fury sees Chen take this stance. When it's clear pacifism isn't getting him anywhere in finding out the truth about his instructor's death, he goes on a one-man rampage against the rival dojo.
- In Star Trek (2009), when Kirk gets accused of cheating on the Kobayashi Maru Test, reprogramming the simulation so that he could win, he argues that "The test itself is a cheat" since it makes highly improbable no-win situations, so it was reasonable for him to cheat his way into a winnable situation.
- TRON: Alan Bradley is reluctant at best to help out Flynn. Part because Flynn's breaking the rules by hacking into the company's system, part because the man incessantly Trolls him and Lora when they're questioning him, and part because...well, Flynn is his fiancee's ex-boyfriend. But then, Flynn lays out the reason behind the hacking - Dillinger stole Flynn's work, using it to make a meteoric rise in the company. Realizing Dillinger (and Master Control) have "broken the rules" convinces Alan to throw his lot in with Lora and Flynn, culminating in a six-felony late-night break-in on company headquarters to get Alan's software (the title character) running and expose Dillinger's crimes.
- Timecop: Foreshadowed well in advance. When Walker and Matuzak are talking about how McComb has been a slippery bastard so far at the very beginning, Walker growls out "if I can't go back in time to save my wife, there's no way I'm gonna let him go back in time to profit." McComb having achieved what he wanted in the second act, Walker goes back in time to Set Right What Once Went Wrong, and sure enough destiny makes it necessary for him to save his wife's life as part of it.
- Discussed in The Lord of the Rings: The Return of the King. In a minor departure from the book, King Théoden of Rohan questions why he should answer Gondor's call if their ally activates the alliance, since Rohan received no aid from Gondor when they were under attack by Saruman in the previous film. However, when Gondor Calls for Aid later, Théoden honors it.
- Heralds of Valdemar series. In Exile's Honour, Alberich is considering whether or not he should help Valdemar, as this would violate his oaths to the Sunpriests. Then he remembers that the priests swore oaths to the Sunsguard as well—and never fulfilled them.
- In The Pendragon Adventure Uncle Press tells Bobby that it's against the rules to bring technology from one Territory to another. The Big Bad Saint Dane does it. In one of the later books, Bobby decides that if Saint Dane can do it he can too and brings a big earth drilling machine from a technologically advanced Territory to one with more medievel level. This helps him stop the emergency of the moment, but it sets up a chain of events that makes him lose ground in the long run.
- The threat of this plays a key role in the Inevitable Mutual Betrayal plot of Skin Game. Through a convoluted series of events, Harry is forced to work for Nicodemus - a member of the series's Big Bad Ensemble - until Nick has accomplished his goal. These two characters absolutely despise each other, but the laws of the magical world prevent them from trying to kill each other while this arrangement stands. One of Harry's goals is to force Nicodemus to throw the first punch so that he can be freed from his obligation to play nice. Thanks to a particularly vicious display of psychological warfare, he succeeds.
- The Discworld book Hogfather concerns a plot by the Auditors of reality to unmake humanity. The Auditors loathe humans for being untidy but have long held an unsteady truce with Death. After a group of them cheats, he wipes them out. Though he could justify this by the fact that they had taken living forms, he uses this trope instead.
Auditor: You can't do this! There are rules!
Death: Yes, there are rules. But you broke them. How dare you. How dare you!
- In The Misenchanted Sword, the war between Ethshar and the Northern Empire comes to an end when the Northern Empire, as an act of desperation, unleashes a horde of demons on Ethshar; this is treated by all sides as if it were an all-out WMD attack. In response, the gods allied to Ethshar break their own rule of non-intervention and wipe the Northern Empire off the map.
- In The Mahabharata, the Pandavas are essentially exiled because they lost a game of dice. One of the many reasons they are angry about this was because the guy they were playing against blatantly and constantly cheated. The cycle of cheating escalates to the point of the Kurushetra war that decimates the Kuru dynasty. The war concludes by Ashwattama, one of the last remaining Kaurava generals, murdering the entire Pandava lineage and their in-laws in their sleep and striking Arjuna's grandson from the deceased Abhimanyu stillborn.
- Sir Etienne, an ally of the protagonist of October Daye, is usually a scrupulously honorable knight who would never pull a dirty move like a Groin Attack...except when the other guy brings an iron weapon to the fight. As almost everyone in the series is some kind of fae and nigh-fatally allergic to the stuff, all bets are off once iron is involved.
- A Discussed Trope in the first Darth Bane novel. Dessel (the future Darth Bane) gets attacked by a fellow miner, and they get into a fistfight. Then the other man attempts to gouge Dessel's eye out... at which point Dessel bites the man's finger off. As Dessel himself notes while the man lay there screaming in pain: you should never escalate a fight unless you're willing to pay the price of losing.
- One of the "Bar Wars" episodes of Cheers revealed that Cheers and Gary's Old Town Tavern had signed a peace accord calling an end to their prank war. But on St. Patrick's Day, the Cheers gang discovers their wooden Indian Tecumseh is missing. Assuming Gary and his gang stole it, the Cheers gang launches a counterattack that shuts Gary's down. Unfortunately, it turns out that Rebecca had Tecumseh sent away to be refinished without telling the others. Fortunately, it turns out that Gary had decided to take a vacation that week and his tavern was closed anyway.
- In an early episode of MythBusters, during a build-off, Jamie was keeping his build within the rules (specifically, the rule saying how much could be spent) until his team found out Adam's team had broken that rule. Cut to Jamie mounting an overbudget component.
- Played with in an episode of Sons of Anarchy. The Sons and the Aryans agree to meet for an unarmed brawl. Knowing the Sons will be unarmed, the Aryans show up packing guns. The Sons then reveal that they had anticipated this treachery and had made deals with two other gangs to cover them from the bushes. Rather than taking advantage of their now superior firepower, the Sons simply insist that the Aryans honor the original deal and fight them unarmed as originally agreed.
- Babylon 5:
- This is implied to be how the ancient conflict between the Shadows and Vorlons started. When the First Ones left the galaxy, the Shadows and Vorlons stayed behind to guide the younger races, the Vorlons by providing structure and stability, and the Shadows by causing conflicts and weeding out the weak. At first they had some sort of agreement and both abode by it, but eventually one of them, it's never said which, decided their way was the only way and violated the agreement. The other reciprocated and thus began the cycle that lasted for millennia if not longer.
- Sheridan accidentally ups the ante on this at the end of the third season. Apparently, the Shadows and Vorlons still had some basic rules, specifically about not using WMDs. Unfortunately, Sheridan didn't know anything about this, so he nuked a city on the Shadow homeworld. In response, the Vorlons assumed that the WMD treaty is now over, so they whip out their Planet Killer, which is rather excessive compared to a nuke. In response to that, the Shadows decide to whip out their planet killers. Basically, the galaxy quickly goes to shit.
- Sheridan caused another rules violation earlier in the third season, as well. The Shadows began attacking younger species openly, and no one was willing to join Sheridan's proposed alliance against them because of how scary they were. Sheridan begged Kosh for direct assistance, which he eventually provided, but only with extreme reluctance. It turns out there was a rule in place that the Shadows and Vorlons wouldn't attack each other directly - so in revenge for the Vorlon attack on their ships, the Shadows assault and kill Kosh in retaliation. Naturally, Kosh never bothered to explain any of this to Sheridan. This event triggers escalating rules violations by both sides.
- Horatio Hornblower plays with this in "An Even Chance". When Jack Simpson decides to cheat in their pistol duel and fire early, Horatio declines to fire back in cold blood (even though it would be within the rules). After Horatio justifies this with Jack being "not worth the powder", Jack decides to go all out, attempting to stab Horatio in the back. It's at this point that Captain Pellew decides to interfere with an improbably but awesomely accurate musket shot.
- In the Netflix revival of Mystery Science Theater 3000, when Jonah and the Bots realize that Kinga and Max have been stealing their riffs for their Invention Exchanges, Kinga blows it off by saying that companies steal things all the time.
- Star Trek:
- In the Star Trek: Deep Space Nine episode "For the Uniform", Maquis leader Michael Eddington launches chemical weapons at a Cardassian colony, then attacks evacuation ships. Captain Sisko responds with his own chemical attack on a Maquis world, and threatens to do the same to others unless Eddington turns himself in. Eddington folds.
- Implied to be the case during the opening battle of the Klingon War on Star Trek: Discovery. T'Kuvma the warlord accepts the offer of a cease-fire from Admiral Anderson — and then uses a cloaked "cleave ship" to destroy Anderson's flagship, an act that falls under the war crime of "perfidy". Captain Georgiou then responds in kind — when T'Kuvma starts recovering the bodies of his fallen warriors, Georgiou booby-traps one of them with a torpedo warhead (which violates part of the 1980 Geneva Protocols), leading to an explosion that cripples T'Kuvma's flagship.
- In general, face tag teams don't enter unless tagged (versus heels, who will often run in to break up a pin, then back off when the ref admonishes them), but when the heels start double-teaming a face member, generally the face team disregards the tag rule, at least until one of the heels is taken out of the ring.
- More generally, faces are somewhat more likely to cheat after the heels do it first, as at that point it's just evening the odds.
- The Clans have a strict dueling code that they use to fight. If it gets violated, though, they have a tendency to go nuts and use all kinds of dishonorable options available to them: calling in reinforcements, ganging up on single targets, or even calling in artillery or airstrikes.
- The Word of Blake is one of the first factions in the game's story to break the Ares Conventions and resort to such tactics as Orbital Bombardment and nuclear weapons. It doesn't take long for the Inner Sphere powers to decide that if the Blakists are going to violate the Conventions so flagrantly, they're not going to be protected by them either, and start nuking the Blakists right back.
- Dungeons & Dragons: One of the archdemons is described as being honorable enough to allow enemies to challenge him to fair combat. If they cheat, however, all bets are off.
- In Temple of Elemental Evil, there is something of an unwritten rule between the Gods of the setting not to directly intervene in mortal affairs. When one of the evil Gods breaks this rule and manifests an avatar to attack your party in the final battle, one of the Good-aligned Gods promptly manifests his own avatar one round later, none too pleased at the breach in protocol and more than willing to answer it in kind. When the two Gods then teleport away to continue their battle in private, the evil God doesn't leave without first raising all of the enemies you'd previously killed during the fight as zombies.... which, in turn, prompts the good God to respond by fully healing your party before he leaves as well.
- This is essentially the reason that both factions in Star Wars: The Old Republic use to defend breaking the Treaty of Coruscant. Given the number of proxy wars, unauthorized secret missions, and espionage going on, (the series is The Cold War IN SPACE after all) neither the Republic nor the Empire was upholding the truce fully to begin with anyway.
- Implied (if not stated outright) in the Kingdom Hearts series. Most Keyblade wielders (and other benevolent inter-worlders) do their best to maintain a world order, and so are generally prohibited from muddling ("Meddling!") in other worlds. The events of the games happen because Unversed, Heartless, and Nobodiesnote are travelling across the Ocean Between and spreading darkness in many different worlds.
- In Tales of Symphonia, the village of Iselia has a non-aggression treaty with the Desians. After a Desian force apparently attacks the Martel Temple, Genis uses this trope as an excuse to visit the Desian human ranch, which is forbidden by the treaty. However, because the "Desians" that attacked the temple were actually a rebel faction known as the Renegades (though this fact isn't revealed until much later in the game), the actual Desians end up invoking this trope themselves and attack Iselia in retaliation.
- Death Battle: The fight between Balrog and TJ Combo starts off as a championship boxing match, but given this is Death Battle, somebody was going to break the rules and go for the killer blow. Balrog is the one who breaks them first, with a grab, headbutt, stomp, and sucker-punch, followed by incapacitating or possibly murdering the referee who tries to disqualify him for it; TJ proceeds to use suplexes and kicks in the ensuing fight, and proceeding to take victory by decapitation.
- Erfworld: The Magic Kingdom prizes its neutrality very highly, so when Jojo gets a squad together to oppose Parson, he warns them they can't attack first or they'll be the criminals. He does end up attacking first, but manages to spin it in his favor by claiming Parson violated the neutrality first. Parson didn't actually violate the neutrality, but he did violate the spirit of the rules by doing a few things everyone thought were impossible.
- The Order of the Stick: The page quote comes from a moment where an important vote, one which had powerful runic protections that would strike and petrify anyone that broke Dwarven law within the location (including vandalism and assault), is interrupted and declared over with no result. The Exarch, a vampire that had been trying to rig the vote, attempts to assault Sigdi (one of those responsible for the interruption) stating nothing prevented him from murdering her; Sigdi answers that since the rules applied both ways, nothing really stopped her or her massive extended family that was also there from returning the favor. He's promptly dragged into the sun and held down until he stops existing.
- In The Nostalgia Critic's scathing review of Patch Adams he balks when Patch's Love Interest is murdered, realizing it would be morally wrong to disrespect the memory of a murder victim and even contemplates quitting the review right then and there. Then he does research on the spot and learns the real murder victim was a male colleague of Dr. Adams and that said Love Interest was a complete work of fiction that completely bastardizes the man the character was based on for drama:
Critic: BAD MOVIE! IT'S A BAD, BAD MOVIE!! I AM SO ASHAMED OF YOU!! BAD MOVIE!! Okay, all bets are off! If this movie can't even represent a dead person by getting his GENDER right, NOT making up a false romance, AND A CHILD MOLESTING STORY, ALL OF IT FABRICATED....
- Bravestarr. The title character once reluctantly agreed to a bargain with Tex Hex, because he knew that Tex was such a compulsive backstabber that he would never honor his own end of the deal, which would then leave Bravestarr free to break it as well.
- In the My Little Pony: Friendship Is Magic episode "Fall Weather Friends", Rainbow Dash and Applejack resort to increasingly dirty cheats in their eagerness to beat each other at a race. At one point Rainbow Dash literally says "That's it! All bets are off!" when she decides to break one of their self-imposed rules after a particularly nasty shove from Applejack. The irony though is that Dash started it when Applejack gained the lead and Dash's ego naturally wouldn't let it stand.
- Samurai Jack ep, "Jack vs Aku". The two decide to settle things through a simple hand-to-hand combat, with Aku claiming he won't use his powers while Jack can't use his sword. It starts out even at first, but not surprisingly, Aku starts going back on his word during the match and eventually it's revealed it was all a ploy to get Jack's sword. But Jack pulls an I Know You Know I Know on him by planting fake swords around the area. Eventually Jack retrieves his real sword, fights him as usual and Aku flees with things pretty much back to normal.
- If one side violates a contract, the other party is no longer bound to it either.note
- Warranties often have clauses that say if the customer treats a product in a way that leads to damage that is outside normal usage of the product, the warranty is void.
- In warfare, this is one of the ways being a Combat Pragmatist can backfire. Sure, if you're the weaker one they'll fall for it once or twice, but a more powerful nation can break the rules in many more ways than a weaker one can, so sometimes, it's better to just stick to the conventions and not call the unbound wrath of the other party on yourself.
- In The American Civil War, the Proclamation of Retaliation was essentially "if you start executing/enslaving prisoners of war, so will we".
- Historically, being declared Outlaw was an invocation of this trope: having broken the law, the convict was no longer granted the protection of the law.
- This bit Japan hard in the lead-up to the Pacific War of World War Two. The limits on naval power under the treaties Japan had signed meant that Japan would always be at a disadvantage to the United States. So Japan decided to break the treaty and start building more ships. The United States, no longer bound by the treaty since Japan broke it, immediately implemented plans and started building more ships than Japan could ever hope to match. One of the reasons for the attack on Pearl Harbor was that Japan was fully aware that if they didn't attack America quickly and force them to sue for peace, the planned expansion of the Pacific Fleet would mean that the Imperial Navy would simply be overwhelmed. Needless to say, that's exactly what happened anyway.
- Then there was the issue of Japan's horrendous treatment of Allied prisoners of war. Needless to say, the Allies weren't happy. One reason why there were few Japanese prisoners apart from the Japanese themselves being averse to such an act is that the Allies themselves would rather kill enemy soldiers than capture them, out of anger towards perceived atrocities.