1. Unreasonable delay in pursuing a right or claim — almost always an equitable one — in a way that prejudices the party against whom relief is sought.
— Also termed sleeping on rights.
“Early in its history, Chancery developed the doctrine that where the plaintiff in equity delayed beyond the period of the statute applicable at law, relief would be refused on the ground of laches even though no specific prejudice to the defendant was shown. Today, in most states, there are statutes of limitations applying to suits in equity. Despite these, however, the doctrine still holds that even if the delay is for a shorter period of time than that of the statute, it may still bar equitable relief if it is unreasonable and prejudicial to the defendant.” John F. O’Connell, Remedies in a Nutshell 16 (2d ed. 1985).
prosecution laches. Patents. In a claim for patent infringement, the equitable defense that the patentee did not timely enforce the patent rights.
2. The equitable doctrine by which a court denies relief to a claimant who has unreasonably delayed in asserting the claim, when that delay has prejudiced the party against whom relief is sought. Cf. LIMITATION(3). [Cases: Equity 67. C.J.S. Equity §§ 128–132.]“The doctrine of laches … is an instance of the exercise of the reserved power of equity to withhold relief otherwise regularly given where in the particular case the granting of such relief would be unfair or unjust.” William F. Walsh, A Treatise on Equity 472 (1930).
