par delictum
(law) The par delictum rule prescribes that a party should not obtain satisfaction from a court of law with where his own conduct is wrongful.
The 'clean hands doctrine', derived from English law, is similar in effect to the Roman law maxim in pari delicto potior est conditio defendentis, which operated as an absolute bar to the grant of relief to the plaintiff. The par delictum rule is concerned with the moral guilt of contracting parties, not their criminal liability.