More stoned workers will be showing up in Canada's workplaces with the coming legalization of marijuana, but companies have few tools to cope with potential safety risks.

That's the message from some employers, who say they've received no assurances from Ottawa so far that the new pot regime will include workplace safeguards.

"We're caught in a potential Catch 22: how do you protect the worker and those around them as well as deal with legalized marijuana?" said Cameron MacGillivray, president of Enform, a Calgary-based oil-and-gas safety group.

"It is a pressing concern for the industry because of the … potential catastrophic impacts of somebody doing a critical safety job when they're impaired."

The Liberal government is expected to introduce legislation by the summer making recreational marijuana legal, at a time when the science of detecting and measuring impairment is incomplete.

Cameron MacGillivray, president of the oil-and-gas safety group Enform, wants the federal government to convene an expert panel to review the science around measuring and testing for marijuana impairment in the workplace. (Enform)

Marijuana is not a new arrival in the workplace, and over the last decade, the legalization of medical marijuana has already made cannabis a more frequent job-related concern.

Full legalization, however, is expected to boost the number of employee users. That's based on spikes in the number of users in Colorado and Washington after recreational pot was made legal there.

"The landscape has changed," said George Waggott, a labour lawyer with McMillan LLP in Toronto, who represents employers.

"The stigma of using marijuana, such as it might have been, is going to be nearly eliminated."

A federal task force report on legalizing and regulating cannabis, released Dec. 13, highlighted "workplace safety" as an issue, especially in the fields of health care, law enforcement, transportation, construction and resource extraction, such as mining.

Under review

"Employer groups called for more guidance from federal, provincial and territorial governments about appropriate workplace drug use and drug testing policies," it noted.

But there were no concrete recommendations, other than to encourage more scientific research on impairment and as well as further consultations with the provinces on the "development of workplace impairment policies."

Employment Minister Patty Hajdu said the government is working closely with the provinces and territories to "come up with a framework that will address substance abuse at work." But she said those consultations are broadly based.

"I think legalization of marijuana is renewing our conversation about substance abuse at work, and I am very, very seized of the issue. But I think there's more to do than just look at marijuana," Hajdu said in an interview with CBC News.

Officials in Employment, Workforce Development and Labour — now headed by Minister Patricia Hajdu — have argued against new regulations for marijuana in the workplace, according to a document obtained by CBC News. (Justin Tang/Canadian Press)

Enform wants the federal government to declare a prohibition against the use of marijuana in safety-sensitive workplaces and for a pre-determined period before workers show up on the job.

It also wants an expert panel to examine and report on how to reliably measure marijuana impairment in workers before full legalization occurs.

An internal document, however, suggests federal officials are not inclined to take any special measures with regard to marijuana in the workplace, preferring to leave the ball in the employers' court.

A July briefing note for then-employment minister MaryAnn Mihychuk, says "it would be premature to make new rules or introduce legislative or regulatory amendments, which may place the labour program and our stakeholders at odds with emerging jurisprudence, until the issues are settled."

"The upcoming legalization of recreational marijuana may require employers to update their alcohol and drug policies to include marijuana use and provide parameters around it as it relates to the type of work being done," the note says.

The document, obtained by CBC News under the Access to Information Act, also acknowledges that testing devices and protocols are still under development.

Special cases

Currently, random alcohol and drug-testing is permitted in Canadian workplaces only in special cases, where there are demonstrable safety risks. However, employers can prohibit drug and alcohol use in the workplace, with some exceptions for medical marijuana patients.

Labour lawyer George Waggott says identifying impairment from marijuana use is the biggest challenge for employers. (McMillan LLP)

Some labour lawyers say they expect no significant changes to those rules, even with the arrival of legalized recreational marijuana.

Rather, the real challenge will be accurately measuring work-related impairment from marijuana, because the science is murky compared with a much clearer understanding of the effects of alcohol, the most commonly abused substance in the workplace.

"The impairment question is the bedrock of where this will be fought," says Waggott.

Another employer group representing federally regulated companies is also pressing Ottawa not to legalize marijuana until the measurement issues have been sorted out.

Derrick Hynes, executive director of FETCO, an employers' association comprised of federally regulated transportation and communications firms — including the CBC — addressed his concerns to the marijuana task force in a submission Sept. 5.

In it he said the government should delay legalization until experts agree on an established definition of marijuana impairment and "the technology exists to test for impairment to this standard in a proven and reliable manner."

'It's what makes marijuana different. There is no "road side test" to determine impairment.' - Derrick Hynes, executive director of FETCO

"It's what makes marijuana different," Hynes said in an interview. "There currently is no 'roadside test' to determine impairment. And further, there is no legislated standard for what level constitutes impairment in an individual."

Toronto employment lawyer Peter Straszynski agrees that the quality of testing methods for marijuana is a problem. But he says the current legal and regulatory regime around drug-and-alcohol prohibition in the workplace and around random-testing may be adequate.

"We do have some framework in place," he said in an interview. "It's not obvious they will have to change it."

But Hynes argues the legalization of recreational marijuana is exactly the right moment for Canada to consider a comprehensive system for random testing in the workplace.

"This is a logical time to have that conversation."