Coloradans who use medical marijuana off the clock can be fired from their jobs for doing so even if they aren’t impaired on the job, an appeals court ruled Thursday in a major decision.

A divided Colorado Court of Appeals panel upheld the firing of a quadriplegic man for off-the-job medical-marijuana use, concluding that, because marijuana is illegal under federal law, employees have no protection to use it anytime.

The 2-1 decision — which is precedent-setting — has broad implications not just for the state’s nearly 109,000 medical-marijuana patients but for any adult using marijuana in Colorado since voters legalized the substance in November. The case is the first to look at whether off-duty marijuana use that is legal under state law is protected by Colorado’s Lawful Off-Duty Activities Statute. The statute says employers can’t fire employees for doing legal things off the clock.

“What the Colorado Court of Appeals said is, by definition, the use of medical marijuana cannot be lawful,” said Vance Knapp, an attorney with Sherman and Howard who specializes in employment law.

In 2010, Dish Network fired Brandon Coats, a medical-marijuana patient, from his job as a telephone operator because he failed a random drug test. Coats — who is wheelchair-bound because of a car accident and says he uses marijuana to control muscle spasms — sued Dish, arguing that his marijuana use was legal under state law and that he was never impaired on the job. Coats said he was a model employee.

“I’m not smoking it just to have fun,” Coats said Thursday. “I really do need it to function in life.”

A trial court upheld the firing, but, in doing so, cited a previous court ruling that said the state’s medical-marijuana law only creates exemptions from prosecution and not rights. Thursday’s ruling by the Colorado Court of Appeals reaches a much broader conclusion: That nothing illegal federally can be considered “lawful” under the Lawful Off-Duty Activities Statute.

“While we agree that the general purpose of (the Lawful Off-Duty Activities Statute) is to keep an employer’s proverbial nose out of an employee’s off-site off-hours business,” Court of Appeals Chief Judge Janice Davidson wrote in the opinion, “we can find no legislative intent to extend employment protection to those engaged in activities that violate federal law.”

Judge Jose Marquez concurred in the opinion.

But Judge John Webb disagreed, saying that the Lawful Off-Duty Activities Statute should be read as only concerning state law. The statute, Webb argued, was intended to protect employees from discriminatory firing.

“If an employee’s off-the-job activity violated only federal criminal law, that activity might well warrant termination based on ‘a bona fide occupational requirement’ of the position,” Webb wrote in his dissent. “But if the employee’s activity was unlawful only under federal law, and it did not relate to such a requirement, then the employee would be protected from termination.”

All three judges agreed, however, in reversing the trial court’s ruling that Coats should have to pay Dish Network’s attorneys’ fees for the case.

Coats said he is disappointed in the ruling, and his attorney, Michael Evans, said he would ask the state Supreme Court to review the decision. Coats said he has had trouble finding work since being fired, and Evans said it is important for all medical-marijuana patients that the case be fought until the end.

“(Coats) was very aware that, with his condition, if he can’t win this case, no one can,” Evans said.

Thursday’s decision comes as lawmakers are debating how to regulate legalized marijuana for anyone 21 and older. Amendment 64, the measure that legalized use and possession of up to an ounce of marijuana for adults, says employers can still create drug policies governing marijuana. A state task force subsequently recommended that section be interpreted as allowing employers to fire employees for off-the-job marijuana use.

Brian Vicente, a marijuana advocate and one of Amendment 64’s authors, said the law is “open to interpretation” whether off-the-job recreational marijuana use is a fireable act. But he said it is unfair to fire medical-marijuana patients for using cannabis.

“They’re basically permitting employers to fire disabled employees, not based on the quality of their work but on the type of medicine they use,” Vicente said of the appeals court’s ruling.

Employers, though, greeted Thursday’s decision with approval. Holli Hartman, an employment law attorney with Baker Hostetler in Denver, said the decision is “a pretty strong ruling for employers.”

The National Federation of Independent Business, which filed an amicus brief supporting Dish Network’s position in the Coats case, also applauded the decision.

“We would not tolerate any attempt to infringe on the employers’ right to a zero-tolerance drug policy,” said Tony Gagliardi, the NFIB’s state director in Colorado.

John Ingold: 303-954-1068, jingold@denverpost.com or twitter.com/john_ingold

Staff writer Aldo Svaldi contributed to this report.