Trevor Hughes

USA TODAY

DENVER — Last month, Colorado diner owner Mark Rose posted an unusual job description: "Looking for part time experienced breakfast cook. Pays well, must be friendly and a team player, could turn into a full time gig by summer. 420 friendly a must."

With that public declaration, Rose put himself squarely in the camp of employers acknowledging that marijuana use is perfectly legal in Colorado. Perhaps more significant, it also puts him in the camp of employers who officially don't care if their employees use pot off-duty. The phrase "420" is shorthand for someone who uses marijuana.

Rose owns Dot's Diner on the Mountain in the pot-friendly mountain town of Nederland, Colo., just west of Boulder. He says he wanted to hire a marijuana-friendly employee to ensure he didn't have to deal with someone who might complain about his own pot use.

Legalized marijuana in Colorado and Washington state is sparking new conflicts between employers trying to maintain drug-free workplaces and workers who say they're being punished for their off-duty indulgences. Nearly half the states now legalize some sort of marijuana use, either for medical purposes or purely for fun.

"I imagine there will be a great deal of upheaval in the future," says Curtis Graves, a staff attorney with the Mountain States Employers Council, which advises companies on workplace issues. He added, "The law is going to be in flux for another 10 years."

Twenty states now permit the use of marijuana for medical reasons, but employers in those states are under no legal obligation to allow any kind of pot use in the workplace. Colorado has a law that says workers cannot be fired for legal activities while off duty, but the state's courts also have said marijuana use isn't lawful because the federal government still considers it an illegal drug.

The result: More employers are testing prospective workers before hiring and continuing random drug tests, says Tiffany Baker, co-owner of the Denver DNA and Drug Center, which provides drug-testing services to employers.

"I think big companies were already testing anyway," she says. "I think small companies are … now more likely to send their workers over."

"Employers have total power in this arena," Graves says. "At this point, the employer can do anything they want to do."

In Washington state, which is still developing its retail marijuana system, there's been little change, says Jenifer Lambert, a vice president of the employment agency Terra Staffing Group, which places about 5,000 workers a year. She says manufacturers and companies that work in federally regulated areas such as interstate commerce and aerospace continue to test job applicants for drug use. Only one of about 500 companies that Terra works with has relaxed its rules.

Lambert says she expects to see increasing conflicts as marijuana becomes more socially acceptable. She says it's ironic because workers rarely complain about a smoke-free workplace that bans cigarette use.

At the same time, she says, some prospective workers are essentially smoking themselves into a corner by using legal marijuana. She says the company doesn't track how many prospective employees are failing drug tests but says there's an increase of people admitting they won't pass.

"It's sort of a Wild West scenario. It's very, very tricky," Lambert says. "I feel badly when someone comes to us and doesn't understand the implication of their pot smoking."

Office manager Dawn Owens, 47, knows all too well what would happen if she got caught using marijuana to ease her migraines. Instead, she takes prescription drugs because those are allowed, even though she feels far less able to work effectively.

"It would literally take two to three puffs off a joint and my headache would be gone within one to two minutes," Owens says. "But instead, I'll be taking a Vicodin, which will render me useless for much of the day," she says.

She says it's hypocritical of employers to permit prescription drug use and to tolerate or even encourage after-work drinking but bar workers from using legal marijuana. "You can hire a raging alcoholic that can pass a test because they haven't had a drink in 24 hours and you can hire someone who abuses prescription drugs because they were able to get a prescription for it, but if someone smokes a joint on a weekend they can't get a job because they can't pass the drug test," she says.

Employers increasingly will have to ask themselves whether they need to shift from testing solely for the presence of marijuana to a test that checks for impairment, says Leslie Miller, deputy counsel for the Manufacturers Alliance for Productivity and Innovation. He says manufacturers are cautious about making any changes that could reduce worker safety. But they also must acknowledge that workers who use marijuana on their own time — on vacation, for instance — aren't breaking any laws, he says.

"What happens if those employees go skiing (in) Aspen or fishing in Washington?" he asked. "Up until now, I think the concern was that marijuana was an illegal activity."

Attorney Rachel Gillette, director of the Colorado chapter of the National Organization to Reform Marijuana Laws, says employer attitudes haven't caught up with the public at large. She says there's no test that can check whether someone is actually impaired, a problem because marijuana often remains in the body for weeks. In contrast, an employer can use a breath test to see whether a worker has been drinking on the job.

"It's a remnant of failed drug-war policy that needs to be looked at again," Gillette says. "It's time for employers to re-think their random drug-screening policies."

Gillette says business owners need to calculate the costs of replacing employees fired from drug-free workplaces. She says otherwise good workers who use pot on their own time shouldn't be punished, especially when employees who drink or abuse prescription drugs don't face the same penalty.

"It's probably not effective to be excluding a large part of the workforce from jobs just because they have used a legal substance in the past 30-60 days," she says.

At Denver International Airport, workers are randomly drug-tested to help ensure safety, said spokesman Heath Montgomery: "Working around aircraft, and on an active airfield, requires focus and clear thinking in order to maintain the safety of the traveling public, as well as employees." DIA workers who test positive for drugs of any kind aren't automatically fired, but a positive test result launches a conversation between employee and employer, Montgomery said.

Owens, the office manager, says her husband uses medical marijuana but struggles to find work because so many employers drug test before hiring. Knowing that he'll test positive, he doesn't bother to apply, she says.

A pending Colorado Supreme Court case between a paralyzed man and his former employer could set a precedent across the country, Graves says. In that case, DISH Network fired former telephone support operator Brandon Coats in 2010 after he tested positive for marijuana. Coats sued the company, arguing that his use of medical marijuana on his own time and in his own home had no bearing on his work. The Colorado Court of Appeals ruled against Coats, deciding that DISH had the right to enforce its drug-free policy. Coats has appealed the decision, with a ruling likely to come later this summer.

Graves says the uncertainty will persist as employers and workers balance safety and personal freedoms and until scientists develop an on-the-spot test that can measure marijuana impairment. Today's tests can take three to five days to process.

In Nederland, diner owner Rose says it's about time America had an honest conversation about how many people have been using marijuana. Having worked in multiple offices, medical clinics and professional settings, he says it's a mistake to think people haven't been using marijuana safely for decades.

He said none of his pot-using employees cause any problems, but he had to fire a worker who repeatedly came to work drunk or severely hung over.

"The dominoes are falling, and they are falling faster than anyone expected," he says. "Guess what? The sky isn't falling."