In international law. Intervention is such an interference between two or more states as may (according to the event) result in a resort to force; while mediation always is, and is intended to be and to continue, peaceful only. Intervention between a sovereign and his own subjects is not justified by anything in international law; but a remonstrance may be addressed to the sovereign in a proper case. Brown.
In English ecclesiastieal law. The preceeding of a third person, who, not being originally a party to the suit or proceeding; but claiming an interest in the subject matter in dispute, in order the better to protect such interest, Interposes his claim. 2 Chit Pr. 492; 3 Chit Commer. Law, 633 ; 2 Hags. Const 137; 3 Phillim. Ecc. Law, 586.
In the civil law. The act by which a third party demands to be received as a party in a suit pending between other persons.
The intervention is made either for the purpose of being joined to the plaintiff, and to claim the same thing he does, or some other thing connected with it; or to join the defendant and with him to oppose the claim of the plaintiff, which it is his interest to defeat Poth. Proc Civile, pt. 1, c 2,