Clayton Hannah says he wanted to be honest with a future employer when he disclosed that he has a medical cannabis prescription, but now believes it cost him a lucrative job offer.

"At first I was really excited, and eager for the opportunity," Hannah told CBC News. "Now I'm disappointed that everything worked out the way it did."

Hannah, who lives in Edmonton, says he received a job offer from Tolko Industries in High Prairie to start working as a millwright on Oct. 9.

The position was safety sensitive, and required Hannah to pass a drug test.

Hannah was concerned that THC from a cannabis oil treatment he had taken to treat his cancer might still be lingering in his system.

He has follicular lymphoma, a form of incurable blood cancer that progresses slowly. Hannah said he was prescribed cannabis oil with a high THC content to experiment with tumour suppression.

I thought honesty would be the best policy, so I told them the truth. - Clayton Hannah

He stopped the cannabis treatment six months ago in order to be clean for his next job. He hasn't experimented with the cannabis oil treatment since.

Hannah disclosed that information to Tolko on Oct. 2.

"I thought honesty would be the best policy, so I told them the truth."

He also asked to see Tolko's drug and alcohol policy, which he said he never received.

The 34 year-old passed his drug test on Oct. 3. CBC obtained a copy of the negative results.

Hannah said someone from Tolko called him the same day.

"They were pulling my job offer, because they could not tell if I was using my prescription or not at work," he said.

Tolko Industries declined to be interviewed by CBC, citing privacy reasons.

Offer withdrawn

Hannah asked for an explanation in writing. Tolko replied that his disclosure meant that an additional third-party assessment into his cannabis use had to take place.

He said he complied and submitted his medical information to the third-party assessor.

But before that assessment could be completed, Hannah said, his relationship with the company became tense.

In an email, Hannah accused the company of discrimination, pointing out that the legalization of cannabis means that any adult could potentially be impaired at work.

"I think it is a bit ridiculous that this is even an issue, to be honest," wrote Hannah.

He repeatedly asked for a written explanation of what was happening with the job offer.

Tolko officially rescinded the offer in a letter on Oct. 15.

"Rather than being patient with the process, you became aggressive, made allegations, and demonstrated an overwhelming lack of trust in Tolko," the company letter said.

"For these reasons, it is clear that an employment relationship would not be viable, and Tolko is withdrawing its conditional offer."

Duty to accommodate

Hannah has filed a complaint with the Alberta Human Rights Commission.

He wants to be compensated for the financial impact of preparing for a move that never happened.

"An apology would go a long way," he said.

Job seekers are protected by human rights codes, said Toronto employment lawyer Andrew Monkhouse.

It would be similar to an employer finding out that someone is dyslexic and pulling back the offer. - Andrew Monkhouse, employment lawyer

Employers have a duty to accommodate potential employees who have a prescription for medical cannabis.

They cannot discriminate against a job seeker with an illness, said Monkhouse.

"It would be similar to an employer finding out that someone is dyslexic and pulling back the offer."

Job candidates don't need to volunteer information about their prescriptions, Monkhouse said.

"If an employer wants to know, or has a policy that requires you to disclose it, they should be the ones making that known to you and asking the questions."

'Heads in the sand'

Hannah's situation highlights the importance of having updated policies to deal with cannabis in the workplace, said Jeff Bradshaw, president of Cannabis Learning Series.

"I think that most companies have had their heads in the sand," Bradshaw said. "They're not sure what to do, so they're waiting to see what happens, and that's the scary part."

He advises employers with safety sensitive jobs to be proactive, or risk workplace accidents or lawsuits.

"Update those policies and take it seriously. It's a little bit like an insurance policy, you don't need it until you need it."

I think that most companies have had their heads in the sand. - Jeff Bradshaw, president, Cannabis Learning Series

Employers should treat medical cannabis prescriptions the same way they treat any other prescription that could potentially impair a worker, said Alison McMahon, founder of Cannabis At Work.

"Disclosure is an important piece, and also making sure that they have an accommodation process in place," McMahon said.

Policies should also reflect the fact that there is no reliable test to determine if an employee is impaired by cannabis on the job, she said.

Employers are better off establishing a cutoff level for how much THC can be present in a worker's body.

"Failing a test means being over a certain cutoff limit, as opposed to trying to say that if you're caught impaired by cannabis there'll be consequences, because that's a far less defensible position."