Employers’ zero-tolerance drug policies trump Colorado’s medical marijuana laws, the Colorado Supreme Court ruled Monday.

In a 6-0 decision, the high court affirmed lower court rulings that businesses can fire employees for the use of medical marijuana — even if it’s off-duty.

With the ruling, which was a blow to some medical marijuana patients and a sigh of relief to employers, Colorado became the first state to provide guidance on a gray area of the law.

The decision came nine months after the state’s highest court heard oral arguments in Brandon Coats’ case against Dish Network. Coats became quadriplegic in a car accident and used marijuana to control leg spasms. He had a medical marijuana card and consumed pot off-duty. He was fired in 2010 after failing a random drug test.

DOCUMENT: Colorado Supreme Court affirms ruling

When the case went to the state Supreme Court, legal observers said the case could have significant implications for employers across Colorado. They noted that the ruling also could be precedent-setting as Colorado and other states wrangle with adapting laws to a nascent industry that is illegal under federal law.

That term, the justices said, refers to activities lawful under both state and federal law.