Laches

Laches is an equitable defense, or doctrine. The person invoking laches is asserting that an opposing party has "slept on its rights", and that, as a result of this delay, that other party is no longer entitled to its original claim. Put another way, failure to assert one's rights in a timely manner can result in claims being barred by laches.

In most contexts, an essential element of laches is the requirement that the party invoking the doctrine has changed its position as a result of the delay. In other words, the defendant is in a worse position now than at the time the claim should have been brought. For example, the delay in asserting the claim may have caused a great increase in the potential damages to be awarded; or assets that could earlier have been used to satisfy the claim may have been distributed in the meantime; or the property in question may already have been sold; or evidence or testimony may no longer be available to defend against the claim.

Under the United States Federal Rules of Civil Procedure, laches is an affirmative defense, which means that the burden of proving laches is on the party asserting it (normally the defendant).