NOLLE PROSEQUI, a phrase used in judicial proceedings, where a plaintiff in an action does not declare in a reasonable time, in which case it is usual for the defendant's attorney to enter a rule for the plaintiff to declare, after which a non prosequitur may be entered. A nolle prosequi is esteemed a voluntary confession that the plaintiff has no cause of action; and therefore if a plaintiff enters his nolle prosequi, he may be amerced; but if an informer cause the same to be entered, the defendant may have costs. The phrase is derived from the words used in the formal entry of the withdrawal, in which the party agrees that he will not farther prosecute (se ulterius nolle prosequi).