LANSING, Mich. (AP) — The Michigan Supreme Court says judges should follow a four-part test before trial to determine whether defendants in cases involving medical marijuana are immune from prosecution.

The court in a unanimous decision released Monday sent two cases back to Oakland County Circuit Court, saying defendants must show they’re entitled to immunity.

The court says a defendant must have had a valid registry identification card, complied with state limits on amounts of medical marijuana; kept marijuana plants in an enclosed, locked facility; and participated in the medical use of marijuana.

The cases involved two medical marijuana patients, including one certified to supply medical marijuana to others.

Michigan voters approved marijuana use for some chronic medical conditions in 2008, but details of what’s legal have been tied up in the courts.