The 6th Circuit ruled last week that Wal-Mart Stores Inc. did not wrongfully fire an employee for his medical marijuana use.

Joseph Casias worked as an inventory-control manager at a Battle Creek, Mich., Walmart beginning in 2004. In November 2009, he injured himself at work and went to the hospital, where he received a standard drug test per Wal-Mart’s policy. He tested positive for marijuana.

Casias, who was previously diagnosed with an inoperable brain tumor and sinus cancer, showed his managers a registry card saying that his oncologist prescribed him the medical marijuana treatment in June 2009 after Michigan voters approved it the year before. He says the drug reduces his pain and improves his speaking abilities. Nonetheless, Wal-Mart fired him.

Casias sued Wal-Mart for violating the Michigan Medical Marijuana Act, which prohibits “disciplinary action by a business or occupational or professional licensing board or bureau” against a “qualifying patient.”

Last year, a federal judge found that Wal-Mart did not improperly terminate Casias. And yesterday, the 6th Circuit upheld the decision, saying that “Michigan law doesn’t stop employers from firing people who use medical marijuana.”

Read Bloomberg BNA and the Huffington Post for more about the 6th Circuit’s decision.

Read more InsideCounsel stories about medical marijuana:

Labor: Employment protections under medical marijuana laws

Medical Marijuana Users Raise Unexpected Issues for Employers

Medical Marijuana Laws Are Spreading Across the Country