Michigan Compiled Laws, Chapter 333. Health § 333.7531

Sec. 7531. (1) It is not necessary for this state to negate any exemption or exception in this article in a complaint, information, indictment, or other pleading or in a trial, hearing, or other proceeding under this article. The burden of proof of an exemption or exception is upon the person claiming it.

(2) In the absence of proof that a person is the authorized holder of an appropriate license or order form issued under this article, the person is presumed not to be the holder of the license or order form. The burden of proof is upon the person to rebut the presumption.

(3) A liability is not imposed by this article or  1 an authorized state, county, or local officer, engaged in the lawful performance of the officer's duties.