Pot may be legal in Colorado, but you can still be fired for using it.

The state Supreme Court ruled Monday that a medical marijuana patient who was fired after failing a drug test cannot get his job back. The case has big implications for employers and pot smokers in states that have legalized medical or recreational marijuana.

Colorado became the first state to legalize recreational pot in 2012. Though the case involves medical marijuana, the court's decision could also affect how companies treat employees who use the drug recreationally.

Brandon Coats is a quadriplegic who was fired by Dish Network after failing a drug test in 2010. The company agreed that Coats wasn't high on the job but said it has a zero-tolerance drug policy.

Courts in California, Montana and Washington state also ruled against medical marijuana patients fired for pot use.

Coats argued that his pot smoking was allowed under a Colorado law intended to protect employees from being fired for legal activities off the clock. Coats didn't use marijuana at work, and he wasn't accused of being high on the job. But pot's intoxicating chemical, THC, can stay in the system for weeks.