Some employers are taking a tougher stance against workers’ drug use since recreational marijuana became legal in Colorado, according to a new workplace survey.

One in five Colorado employers reported that they have implemented more stringent drug-testing policies in the wake of passage of Amendment 64 in 2012.

Only 2 percent of responding companies said they have relaxed their testing for marijuana; 71 percent reported no changes in screening since legalization.

The survey, by Denver-based Mountain States Employers Council, queried 1,648 members of the organization. Responses were sent by 334 companies.

“There seems to be a movement toward more testing,” said Curtis Graves, a staff attorney with the employers group. “A lot of people are freaked out” about the prospects of employees’ legal marijuana use.

Graves said increased testing may be a result of several factors, including aggressive marketing to Colorado employers by drug-test vendors and a campaign to make companies aware that costs for workers’ compensation are lower for businesses that test.

Advocates for legal marijuana say it should be treated the same as alcohol, with no workplace sanctions if employees consume it responsibly off the job.

Despite marijuana’s legal status in Colorado, courts have ruled that employers have the right to fire workers for using pot, even off-duty.

In a split decision last year, the Colorado Court of Appeals upheld the dismissal of a Dish Network employee who admitted he used medical marijuana off the job but said he was never impaired at work.

The court said Colorado’s Lawful Off-Duty Activities Statute, which protects workers from being fired for engaging in legal acts, did not apply because of marijuana’s illegal status under federal law. That decision is under appeal to the Colorado Supreme Court.

Fairfield & Woods employment law attorney Michelle Magruder

said the appeals-court ruling gave assurance to employers that their drug-testing policies are valid and enforceable. She said that may be reflected in the survey results indicating a more stringent testing approach.

The court case showed employers that “it’s OK to continue your policies on drugs and alcohol, and to implement drug-free workplaces,” Magruder said.

Among other findings of the Mountain States Employers Council survey:

• 77 percent of respondents said they test for drugs either in pre-employment screenings or during employment.

• Of those that test, 97 percent screen for marijuana and cocaine, 96 percent for opiates and 95 percent for amphetamines. Seven percent test for alcohol.

• 53 percent of testing employers said they would fire a worker for a first-time positive test for marijuana, and 12 percent would allow an employee to return under probationary conditions.

Mason Tvert, of the pro-legalization advocacy group Marijuana Policy Project, said the survey had suspect methodology that produced biased results.

He said the 20 percent response rate to the survey was “abysmal,” and noted that members of the Mountain States Employers Council are more inclined to have stringent testing policies than employers in general.

“The people most likely to respond to something like this are the ones that are far more likely to conduct testing in the first place,” he said. “I don’t think there should be a conclusion that businesses are cracking down more, based on a survey that has flawed methodology.”

Graves, of the employers council, agreed that the group’s membership is highly focused on workplace issues and may be predisposed toward drug testing.

Marijuana Industry Group executive director Michael Elliott said employers “continue to have the power to have any marijuana policy they want, including zero tolerance.

“Coloradans can be fired from their jobs for failing a drug test, even if the drug test reveals only trace amounts of marijuana that could have been consumed in a legal place outside of the workplace,” he said. “The question remains whether employers are justified in having that much control over the private lives of their employees.”

Steve Raabe: 303-954-1948, sraabe@denverpost.com or twitter.com/steveraabedp