Most self-medication with marijuana remains illegal, and is grounds for discharge.

A federal court has ruled that a worker's self-administration of an illegal drug for pain relief was grounds for discharge under an employer's drug policy. The case highlights the problems employers will face as more workers receive the right to obtain medical marijuana to treat various disabling conditions.

Recent case: Michael worked as an engineer for PECO, the electric company that serves the Philadelphia region. The company has a zero-tolerance policy for illegal drug use and conducted random drug tests on its workers.

Michael had undergone foot surgery in 2016 and recovered slowly. His doctors finally cleared him to work without any restrictions and prescribed no medications of any kind.

About six months later, Michael was picked for a random drug screen. He failed, testing positive for marijuana. Company policy called for termination, but also provided for an automatic referral to drug treatment through its employee assistance program. Michael went for drug treatment. It was paid leave, authorized as FMLA leave.

After completing...