Joseph Casias, 29, has sinus cancer and an inoperable brain tumor.

Despite his condition, he has dutifully gone to work every day for the last five years at a Walmart in Battle Creek, Michigan, where in 2008 he was named Associate of the Year.

Casias is also a legal medical marijuana patient under Michigan state law. He uses marijuana with the recommendation of his doctor to relieve the effects of cancer.

But Walmart, the world’s largest public corporation, has no sympathy for his condition or regard for Michigan’s state law. Last November, Walmart fired Casias because he tested positive for marijuana during a routine drug screening.

Here’s what a Walmart spokesman had to say:

“In states, such as Michigan, where prescriptions for marijuana can be obtained, an employer can still enforce a policy that requires termination of employment following a positive drug screen. We believe our policy complies with the law and we support decisions based on the policy.”