The free and voluntary act of a party himself, done without the suggestion or influence of another person, is said to be done of his mere motion, ea mero motu, (g. v.) Brown.
The phrase is used of an interference of the courts of law, who will, under some circumstances, of their own motion, object to an irregularity in the proceedings, though no objection has been taken to the informality by the plaintiff or defendant in the suit. 3 Chit. Gen. Pr. 430.