unclean handsnoun plural
Legal Definition of unclean hands
: an equitable doctrine: a complainant will be denied relief if he or she has engaged in misconduct (as acting in bad faith) directly relating to the complaint also : the condition of having engaged in such misconduct and being barred from equitable relief may not be invoked by a plaintiff with unclean hands — Royal Sch. Labs., Inc. v. Town of Watertown, 358 F.2d 813 (1966)
Note: Unclean hands on the part of the plaintiff is often pleaded as an affirmative defense by the defendant.