A construction company discriminated against an employee when it fired him after his pre-employment drug test showed traces of marijuana, an Alberta judge has ruled.

Justice Sheilah Martin said the man should have been treated like someone with a drug addiction, and that is considered a disability in a growing body of human rights case law across Canada.

Marijuana testing can be discriminatory, court rules.
(CBC)

It is believed to be the first time that Alberta's Court of Queen's Bench has addressed the issue of pre-employment drug testing under human rights legislation, the Canadian Press said.

The ruling is "important for all workers," said Leanne Chahley, an Edmonton labour lawyer who regularly represents unions. It means that a worker does not have to be disabled to challenge a policy as discriminatory, she said.

It also means that companies cannot use drug tests to weed out potential employees who test positive.

"It's not your employer's [business] if it doesn't affect your work."

"No one wants to encourage impairment at work, but a drug test is an invasion of your privacy," Chahley said.

"It shouldn't matter to your employer what you might do on off-duty time. That's your business. It's not your employer's [business] if it doesn't affect your work."

The case began in 2002 when John Chiasson was hired by Kellogg Brown & Root for a job as a receiving inspector at Syncrude's oil sands plant north of Fort McMurray, Alta.

As a non-unionized employee, he was required to pass a pre-employment drug test.

After taking the test, Chiasson was immediately put to work. Nine days later, the company learned his urine was positive for the active ingredient in marijuana. He admitted he had smoked pot five days before the test and was immediately fired, as called for by the company's zero-tolerance policy.

Chiasson complained to the Alberta Human Rights Commission, which ruled he was not discriminated against. But Martin overturned that decision in a ruling handed down last month.

Worker never used drugs at work

Though Chiasson never used drugs at work, the policy treated him as if he had, the judge wrote. The requirement that he be tested for drugs, with an automatic penalty for a positive result, is discriminatory, she added.

Alberta human rights legislation prohibits discrimination under 13 grounds, including race, religious beliefs and physical and mental disabilities.

Andrew Robertson, the Calgary lawyer representing Kellogg Brown & Root, said he could not comment on the decision. Company officials could not be reached.