Police forces across Canada will have new powers to crack down on drug-impaired driving after the holiday weekend, federal Justice Minister Rob Nicholson reminded Canadians on Friday.

Beginning Wednesday, officers will be able to gather evidence against drivers suspected of being high behind the wheel.

Drug-impaired driving is already a Criminal Code offence, but the new legislation will compel those drivers to take a roadside test, such as walking a straight line.

'We are today with drugs and driving where we were with alcohol and driving 15 years ago.'—Gregg Thomson, father of teen killed in accident

They can also be taken to a police station for more intensive tests. If they fail those, they could be ordered to give a blood, urine or saliva sample.

Refusing the roadside test would be a criminal offence, as is the case for refusing a breathalyzer.

"As of July 2, if you are caught driving impaired, you will be held fully accountable for your actions,” Nicholson said as he and representatives of Mothers Against Drunk Driving (MADD) praised the new measures.

Stan Thomson was 18 when he and four friends were killed in a car crash nine years ago. They were involved in a pileup outside Ottawa that was triggered by a teenager in the group of friends who pulled out to pass. He and the others had been smoking marijuana.

Father takes on mission

Thomson's father, Gregg of Kanata, Ont., has been campaigning against drug-impaired driving since his son's death.

"We are today with drugs and driving where we were with alcohol and driving 15 years ago. We are that far behind the curve, so many more people are going to die before we get this resolved," he said.

Doug Beirness, a research manager with the Canadian Centre on Substance Abuse, said the problem of drug-impaired driving may not be at the level of drunk driving, but it's still substantial.

"When we look at data from drivers who die on the roadways, up to 30 per cent of them test positive for some substance other than alcohol," he said.

The new law will also cover impairment from prescription drugs that have been taken incorrectly.