Estoppel by laches is an equitable doctrine by which some courts deny relief to a claimant who has unreasonably delayed or been negligent in asserting a claim. A person invoking laches should assert that an opposing party has slept on his/her rights and that the party is no longer entitled to his/her original claim. Laches is a form of estoppel for delay.
The following is an example of a case law defining estoppel by laches :
Doctrine of estoppel by laches is the neglect or omission to assert a right for an unreasonable and unexplained length of time, under circumstances prejudicial to an adverse party.[McNeir v. McNeir, 178 Va. 285, 291 (Va. 1941)]