Laches
Definition
Laches is an equitable defense barring a claim when the plaintiff unreasonably delayed in asserting their rights, and the delay caused prejudice to the defendant. Unlike a statute of limitations, which sets a fixed deadline, laches is discretionary and depends on the circumstances. The defendant must show both unreasonable delay by the plaintiff and resulting prejudice (such as loss of evidence, changed circumstances, or detrimental reliance). Laches is most commonly raised in equity proceedings and may bar claims even before the statute of limitations expires.
Example
A trademark owner knows about an infringer for 10 years but does nothing. When the owner finally sues, the infringer raises laches because it invested heavily in the mark during the delay.