KITCHENER – The number of drug-impaired driving charges are up since the legalization of cannabis a year ago, but the numbers were trending up for the last five years.

In most cases, drug-impaired charges involve more than one drug.

Cannabis was legalized in Canada on Oct. 17 of last year. Since then, police say there isn't necessarily more people driving impaired by drugs.

Instead, they say there have been improvements with sobriety field testing.

More than 300 officers in Waterloo Region are trained for it, with 14 specialized in drug-impaired testing.

Recently a new device is allowing officers to test for THC or cocaine in the saliva of drivers.

"It’s for testing drugs in a person's saliva, and yes, that's associated with provincial sanctions that are in place for zero tolerance," explains Staff Sgt. Mike Hinsperger.

"So you would include in that G1, G2, young drivers, M1, M2 drivers and commercial drivers."

He says that when they find a driver with one of those classifications and there's a suspicion of using drugs, they eliminate any concerns for impairment.

From there, the saliva is tested to ensure that there are no drugs in their system.

So far this year, officials say they have laid 75 drug-impaired while driving charges.

Drug-impaired driving charges up since legalization, but not because of it