Wisconsin Statutes Criminal Procedure (Ch. 967 to 980) § 973.077. Burden of proof; liabilities

(1) It is not necessary for the state to negate any exemption or exception regarding any crime in any complaint, information, indictment or other pleading or in any trial, hearing or other proceeding under s. 973.076. The burden of proof of any exemption or exception is upon the person claiming it.

(2) In the absence of proof that a person is the duly authorized holder of an appropriate federal registration or order form, the person is presumed not to be the holder of the registration or form. The burden of proof is upon the person to rebut the presumption.

(3) No liability is imposed by ss. 973.075 to 973.077 upon any authorized law enforcement officer or employee engaged in the lawful performance of duties.