SET-OFF. A claim which is due from a plaintiff to a defendant in an action. and which .the latter is allowed to interpose as total or partial defense to the plaintiff's de mands, and which may result in a judgment in favor of the defendant. The doctrine originated in equity practice and was not known to the common-law courts until the statute of 9 Geo. II., eh. 22, which provided that a defendant might reduce or defeat a plaintiff's demands by proving a just elaim in his favor against the latter. The provisions of the above statute have been substantially followed in most of the United States.
The law authorizing a set-off to be pleaded is permissive and not mandatory, and it is, there fore, optional with a defendant as to whether he will exercise the right or reserve his claim for a separate action. A set-off is only per mated in actions arising out of contracts, and limited to liquidated demands, or those which can be reduced to a certain amount merely by computation. Therefore a claim in tort, as for malicious proseeution, cannot be a set-off in an action. as it is necessarily nnliquidated, and the
amount of damages must rest in the discretion of the jury. At common law a set-oil' must be based upon a distinct claim. In most jurisdic tions the claims must he mutual in order to al low a set-off, that is, they must he confined solely to the original parties to the action. However, in some States a claim existing in favor of de fendant and another against the plaintiff may be a set-off against the latter's claims to the ex tent of defendant's interest, but an affirmative judgment cannot he obtained.
The facts constituting defendant's claim to a set-off must be specially pleaded with as much clearness as if they were the basis of an inde pendent action. The jurisdiction of a court of equity to grant a set-oil' is independent of statutes. Consult: Waterman, Law of Recoup ment, Set-off, and Counter-claim (New York, 1872) ; Barbour, Lou' of Set-off (Albany, 1841). See PLEADING.