Wis. Stat. § 806.35: Asserting and defending a foreign-money claim.

(1) A claimant may assert a claim in a specified foreign money. If a foreign money is not asserted, the claimant makes a claim for a judgment in U.S. dollars.

(2) An opposing party may allege and prove that the claim is, in whole or in part, for a different money than that asserted by the claimant.

(3) Any party may assert a defense, setoff, recoupment or counterclaim in any money without regard to the money of other claims.

(4) The determination of the proper money of the claim is a question of law.