When it comes to medical marijuana, Colorado employers are caught between conflicting laws.

The state’s medical-marijuana amendment, passed by voters in 2000, says that employers don’t have to accommodate medical-marijuana use in the workplace.

But another Colorado law, enacted a few years ago to protect cigarette smokers, prohibits firing employees for engaging in legal activities during nonworking hours.

That suggests that people who smoke medical marijuana before arriving at work could be protected under state law, whether their employers like it or not. And with roughly 30,000 Coloradans now estimated to be qualified to use medical marijuana, employers are growing increasingly uneasy.

It’s the kind of quandary employers in other states are have faced as well, as medical marijuana gains increasing acceptance.

“No cases have been litigated yet in Colorado, so we’re not sure how a court might rule or how a jury might find,” said Danielle Urban, an attorney with Fisher & Phillips LLP, a Denver-based employment law firm.

State courts in California, Washington, and Oregon have handled cases involving employees that were terminated for medical-marijuana use, and they all have sided with employers, she said.

However, none of those states had a law similar to Colorado’s “Unlawful prohibition of legal activities as a condition of employment” statute.

“We’re advising employers not to outright fire someone, although there’s case law in other states, including California—which is pretty liberal—saying that you can do that,” Urban said. “We’re just advising them to try to figure out if there’s some way you can accommodate the employee without firing them or agreeing that they can use medical marijuana.”

For instance, employers could offer a leave of absence for the duration of the employee’s medical-marijuana treatment, Urban said.

With Colorado’s Amendment 20, “It’s the phrase ‘in the workplace’ that’s troublesome,” said Dean Harris, a staff attorney for the Mountain States Employers Council Inc. in Denver. “I believe it is connected with the workplace so long as there is a positive drug test or there is some indication of intoxication while the person is at work. That brings it to the workplace.”

But other lawyers say it may be more complicated than that.

“An employer can always send an employee home if they’re under the influence,” said Vance Knapp, an employment attorney at Sherman & Howard LLC in Denver. “The tricky issue becomes what happens if an employer does a random drug test and an employee tests positive, but says ‘I’m not intoxicated; I’m using this on my own time to treat my chronic disease.’”

Unlike alcohol, elements of marijuana use can be detected for days or even weeks, making it difficult to determine how recently the drug was used.