Wisconsin Statutes Civil Procedure (Ch. 799 to 847) § 802.07. Counterclaim and cross claim

(1) Counterclaim. A defendant may counterclaim any claim which the defendant has against a plaintiff, upon which a judgment may be had in the action. A counterclaim may or may not diminish or defeat the recovery sought by the opposing party. Except as prohibited by s. 802.02(1m), the counterclaim may claim relief exceeding in amount or different in kind from that sought in the pleading of the opposing party.

(2) Counterclaim maturing or acquired after pleading. A claim which either matured or was acquired by the pleader after serving the pleading may, with the permission of the court, be presented as a counterclaim by supplemental pleading.

(3) Cross claim. A pleading may state as a cross claim any claim by one party against a coparty if the cross claim is based on the same transaction, occurrence, or series of transactions or occurrences as is the claim in the original action or as is a counterclaim therein, or if the cross claim relates to any property that is involved in the original action. Except as prohibited by s. 802.02(1m), the cross claim may include a claim that the party against whom it is asserted is or may be liable to the cross claimant for all or part of a claim asserted in the action against the cross claimant.

(4) Joinder of additional parties. Persons other than those made parties to the original action may be made parties to a counterclaim or cross claim in accordance with ss. 803.03 to 803.05.

(5) Separate trials; separate judgments. If the court orders separate trials as provided in s. 805.05(2), judgment on a counterclaim or cross claim may be rendered in accordance with s. 806.01(2) when the court has jurisdiction so to do, even if the claims of the opposing party have been dismissed or otherwise disposed of.