1. Proper attention in proper time. 2. The law requires a man who has a claim to enforce it in proper time, while the adverse party has it in his power to defend himself; and if by his neglect to do so, he cannot afterwards establish such claim, the maxim vigilantibus non dormientibus leges subserviunt, acquires full force in such case. For example, a claim not sued for within the time required by the acts of limitation, will be presumed to be paid; and the mere possession of corporeal real property, as if in fee simple, and without admitting any other ownership for sixty years, is a sufficient title against all the world, and cannot be impeached by any dormant claim.
Law Dictionary – Alternative Legal Definition
Watchfulness; precaution ; a proper degree of activity and promptness in pursuing one’s rights or guarding them from infraction, or in making or discovering opportunities for the enforcement of one’s lawful claims and demands. It is the opposite of laches. Vigilantibus et non dormientibus jura subveniunt. The laws aid those who are vigilant, not those who sleep upon their rights.