Michigan

Michigan Compiled Laws 333.26422 Findings, declaration.

2. Findings.
(b) Data from the Federal Bureau of Investigation Uniform Crime Reports and the Compendium of Federal Justice Statistics show that approximately 99 out of every 100 marihuana arrests in the United States are made under state law, rather than under federal law. Consequently, changing state law will have the practical effect of protecting from arrest the vast majority of seriously ill people who have a medical need to use marihuana.
(c) Although federal law currently prohibits any use of marihuana except under very limited circumstances, states are not required to enforce federal law or prosecute people for engaging in activities prohibited by federal law.

Casias v. Wal-Mart Stores, 695 F.3d 428 (6th Cir. 2012)