Copyright misuse is an equitable defense against copyright infringement in the United States allowing copyright infringers to avoid infringement liability if the copyright holder has engaged in abusive or improper conduct in exploiting or enforcing the copyright. Copyright misuse is comparable to, and draws from precedents under, the older doctrine of patent misuse, which dates back to the early years of the 20th century and derives from the more general equity doctrine of "unclean hands", which bars a party from obtaining equitable relief (such as an injunction) against another when the party has acted improperly (though not necessarily illegally).