Laches is an equitable defense, or doctrine. A defendant who invokes the doctrine is asserting that the claimant has delayed in asserting its rights, and, because of this delay, is no longer entitled to bring an equitable claim. Failure to assert one's rights in a timely manner can result in claims being barred by laches: it is a maxim of equity that, "Equity aids the vigilant, not the negligent."

However, delay alone is not enough to prevent a claimant obtaining relief. The consequence of the delay must be that it would be unfair for the court to give relief, usually because the defendant has changed its position because of the delay.

The party asserting laches has the burden of proving that it is applicable. Laches is distinguishable from the statute of limitation, which prevents a party from asserting claims after the designated limitations period has expired.