Judge John Webb dissented in the split decision, saying he couldn't find a case addressing whether Colorado judges should consider federal law in determining the meaning of a Colorado statute.
Marijuana supporters say the courts are discriminating against them because Colorado's Lawful Off-Duty Activities law, the provision protecting cigarette smokers, prevents workers from being fired for legal behavior off the clock.
The court said lawmakers could act to change the law to protect people who use marijuana, but there have been no plans to do that at the state Capitol.
Coats told reporters Thursday afternoon that he obtained a prescription for medical marijuana to deal with debilitating muscle spasms that would otherwise prevent him from working. He has been looking for a job ever since being dismissed by Dish.
"I'm not going to get better anytime soon," said Coats. "I need the marijuana, and I don't want to go the rest of my life without holding a job."
The Washington state Supreme Court also has found that workers can be fired for using marijuana, even if authorized by the state's medical marijuana law.
Last year, a federal appeals court ruled against a cancer survivor in Battle Creek, Mich., who was fired from his job with Wal-Mart Stores Inc. after failing a drug test for marijuana. Joseph Casias had a medical marijuana card and said he used pot to alleviate symptoms of an inoperable brain tumor.
According to the Marijuana Policy Project, the California Supreme Court also has ruled that people could be fired for testing positive for marijuana. The Legislature passed a bill to change that in 2008, but it was vetoed.
Associated Press writers Colleen Slevin, Peter Banda, Nicholas Riccardi and Eugene Johnson contributed to this report.