735 ILCS 5/12-636: Asserting and defending foreign-money claim.

(a) A person may assert a claim in a specified foreign money. If a foreign-money claim is not asserted, the claimant makes the claim in United States dollars.

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

(c) A person may assert a defense, set-off, recoupment, or counterclaim in any money without regard to the money of other claims.

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