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Laches (/ˈlætʃɨz/; f. French, lâchesse, lâches) ^[1] is an "unreasonable delay pursuing a right or claim...in a way that prejudices the [opposing] party" ^[2] When asserted in litigation, it 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, circumstances have changed such that it is no longer just to grant the plaintiff's original claim. Put another way, failure to assert one’s rights in a timely manner can result in a claim's being barred by laches. Laches is a form of estoppel for delay. In Latin,

Vigilantibus non dormientibus æquitas subvenit.

Equity aids the vigilant, not the sleeping ones (that is, those who sleep on their rights).