Unclean hands

Clean hands, sometimes called the clean hands doctrine or the dirty hands doctrine, is an equitable defense in which the defendant argues that the plaintiff is not entitled to obtain an equitable remedy because the plaintiff is acting unethically or has acted in bad faith with respect to the subject of the complaint—that is, with "unclean hands". The defendant has the burden of proof to show the plaintiff is not acting in good faith. The doctrine is often stated as "those seeking equity must do equity" or "equity must come with clean hands". This is a matter of protocol, characterised by A. P. Herbert in Uncommon Law by his fictional Judge Mildew saying (as Herbert says, "less elegantly"), "A dirty dog will not have justice by the court".

The clean hands doctrine is used in U.S. patent law to deny equitable or legal relief to a patentee that has engaged in improper conduct, such as using the patent to extend monopoly power beyond the claims of the patent.

A defendant's unclean hands can also be claimed and proven by the plaintiff to claim other equitable remedies and to prevent that defendant from asserting equitable affirmative defenses. In other words, 'unclean hands' can be used offensively by the plaintiff as well as defensively by the defendant. Historically, the doctrine of unclean hands can be traced as far back as the Fourth Lateran Council.

Equitable remedies are generally remedies other than the payment of damages. This would include such remedies as obtaining an injunction, or requiring specific performance of a contract. Before the development of the courts of equity in England, such remedies were unavailable in the common law courts, which were usually under the aegis of the local ducal noble, whereas equity flowed from the circuit-riding presence of the King's Chancellor who brought along his retainers to enforce his orders (in this sense, the development of the equity courts was a political effort by the Crown to further limit the power of local nobles). Such remedies were developed in the equity courts, as the payment of damages was often not a sufficient remedy for a plaintiff in certain circumstances. For example, if a landowner polluted the land of the neighbor, the common law tort of nuisance would only allow the innocent party to recover damages. Common law had no remedy that would force the defendant to stop the pollution. Equity courts developed such a remedy, the injunction, that provided an ongoing bar to the activity that caused the damage, as well as affirmative orders called mandamus which compelled a directed party to do a certain thing (which the Chancellor could enforce while there).

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