A Nova Scotia woman has plans to challenge how police test cannabis impairment after her saliva tested positive for the drug when she was pulled over at a roadside checkpoint.

Michelle Gray of Middle Sackville, N.S., who has multiple sclerosis, uses dried cannabis flower and cannabis oil to treat her symptoms.

Gray says that she was pulled over on January 4 by RCMP officers during a routine traffic check. At the time, she says she was unconcerned because she had not consumed cannabis for at least six hours before getting behind the wheel. Her teenage son was also in the car.

The device used, however, does not test for intoxication, but simply for the presence of intoxicating psychoactive cannabinoid tetrahydrocannabinol (THC) in saliva, which remains in the body long after acute effects have worn off.

Gray was even appalled to discover that even after having passed a sobriety test, her driver’s licence was suspended for one week and her vehicle impounded by authorities.

She took a more intensive sobriety test at Halifax Regional Police headquarters, which she also passed, although she had serious concerns that the symptoms of her illness could affect her test results.

Gray was not charged with impaired driving.

“If I would have had a flare-up where my speech was impaired, like it has been during flare-ups in the past, I would have instantly failed,” Gray told CTV News, saying that she had to pay nearly $300 to reclaim her vehicle and missed four days of work as a result of the incident.

“It was a traumatic event for me,” says Gray. “Just because I tested positive for that roadside test for impairment does not mean I was impaired.”

Gray says she has consulted with a lawyer and intends to challenge the law in court.