Medical cannabis user Michelle Gray won a small victory on Thursday when police said they would cover the $253 cost to get her car back after it was towed when she failed a roadside saliva test, but passed a sobriety test at a Halifax police station.

However, RCMP said they would not be changing their testing practices.

"They are a good tool to further our grounds to make an arrest and then leading to subsequent testing in the form of a blood draw or a drug influence evaluation," said Const. Chad Morrison, a drug recognition expert co-ordinator for the RCMP in Nova Scotia.

Gray, who uses cannabis for multiple sclerosis, said she explained to the officer at a routine RCMP check stop on Jan. 4 that it had been nearly seven hours since she last consumed pot.

She was released without a charge after spending hours at a Halifax police station taking an extensive sobriety test — a 12-step process designed to detect impairment.

Legal challenge

Gray plans to challenge the legality of roadside saliva tests that critics say are unreliable in determining a person's sobriety.

She was arrested after testing positive for THC, the psychoactive ingredient in cannabis. THC is stored in the fat cells and can remain detectable in a person's body for as long a month after usage, according to the Mayo Clinic.

Michelle Gray is planning to challenge the legality of roadside saliva tests, which critics say are unreliable in determining impairment. (Submitted by Michelle Gray)

A Vancouver law firm, Acumen Law, has teamed up with Gray to challenge the legality of the Dräger DrugTest 5000 roadside test and Nova Scotia's roadside suspension provision.

Morrison said police made an error in suspending Gray's licence for seven days, when the maximum suspension they would be able to issue in her case would be 24 hours.

Several cities across Canada, including Ottawa, have decided against using the device due to the questions being raised about the machine's accuracy, especially in cold weather.

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