In tort law, “unclean hands” is a doctrine that prevents one party to a lawsuit from receiving a particular outcome to a case because that party has also engaged in bad behavior.
For instance, if a plaintiff asks the court for an injunction to stop the defendant from dumping his trash in the plaintiff’s backyard, the defendant may argue that the plaintiff has also dumped her trash in the defendant’s backyard, and so the plaintiff has “unclean hands” and should not receive the injunction she wants. The doctrine is based on an idea of basic fairness: One person should not be able to stop another person from doing a bad action if the first person is also doing it.
In most cases, the “unclean hands” doctrine only applies to equitable remedies, not to remedies like payment of damages. For instance, if the plaintiff in the above example asks the court for an injunction to stop the defendant dumping his trash in her yard, the court might find that “unclean hands” applies to the plaintiff, who is also dumping her trash in the defendant’s yard. However, if the plaintiff asks the court to order the defendant to pay for the cost of hauling away the trash he dumped in her yard (plus compensatory damages for her distress or even punitive damages for his bad behavior), the defendant may not be able to argue that “unclean hands” means he shouldn’t have to pay. However, the defendant can still counter-sue the plaintiff for the costs of hauling away her trash.
Although “unclean hands” is often seen as an affirmative defense, it is not, like most affirmative defenses, something that only the defendant can use. A plaintiff can also argue “unclean hands” if a defendant brings up another affirmative defense that seeks an equitable result, such as an injunction.
The “unclean hands” argument often comes up in contracts cases, where both parties have acted in bad faith, yet one still wants the court to make the other do something (often, what the party said he would do under the contract but didn’t) or to stop doing something. When one party breaches a contract, the other has a responsibility to act in good faith by upholding her end of the bargain as much as possible. If the other party decides “well, if you won’t do what you promised then neither will I,” she may find later that the “unclean hands” rule prevents her from enforcing the contract against the person who breached it.
The “unclean hands” doctrine is not the same as the “mitigation of damages” requirement, but the two rules are similar. In a personal injury case as well as in a contracts case, the law in most states expects the injured person to work to keep her damages as small as possible. For instance, an injured plaintiff should seek medical care for her injury instead of letting it get worse.
After an injury, most people will naturally do things that mitigate their damages, because many of these actions are in the injured person’s best interests. However, a plaintiff who does not mitigate her damages risks having a court reduce any damages she wins in a lawsuit against the defendant. “Failure to mitigate damages” is an affirmative defense in most U.S. states.