A police officer’s opinion about a driver’s level of impairment can be admitted as expert testimony at drugged-driving trials without prior examination of the evidence, the Supreme Court of Canada has ruled.

Police officers can administer field sobriety tests for suspected drug impairment, but unlike alcohol, there’s currently no roadside test such as a breathalyzer.

There is also no legal blood-concentration driving limit for marijuana or other drugs. Therefore, in drug-impairment cases, the courts must rely on the specially trained police officers known as drug recognition experts, or DREs, sometimes referred to as evaluators. Police officers train to become DREs through a 12-step program that includes tests on an individual’s eyes, attention, blood pressure and pulse.

In its 5-2 decision released Thursday, the Supreme Court ruled that an evaluator’s opinion can be admitted as expert evidence at trial without first submitting to a voir dire, or preliminary examination of the evidence.

That means that DREs can essentially avoid being subject to attacks on their credibility by defence lawyers in a voir dire scenario, says CTV legal analyst Edward Prutschi.

“That goes a long way towards getting a conviction,” Prutschi told CTV News Channel Thursday. “Makes it very difficult for defence lawyers like myself, (but) not impossible.”

The ruling could effectively mean quicker trials for cases of suspected drug-impaired driving, since the ruling gives legal weight to DREs’ testimony.

“They are considered experts, their opinion is given the weight of expertise in court,” Prutschi said.

He said that the people “who are happiest about this are going to be police officers and Crown prosecutors because it does pave a path for easier prosecution of drug-impaired driving, which … is becoming an increasingly difficult problem to deal with.

“And in particular, when we start talking about blending that with some form of decriminalization or legalization of marijuana, the likelihood that we’re going to see more and more of that, is a real concern to police forces all across Canada.”

The decision means the case involving Carson Bingley of Ottawa will proceed to a third trial. In 2009, Ottawa police charged Bingley with driving while impaired after he cut off a driver, crossed the centre line nearly colliding with oncoming traffic. He later struck a car in a parking lot.

An officer on scene said Bingley showed signs of intoxication, however, an alcohol screening test found his blood-alcohol concentration well below the legal limit.

Bingley failed a standard field sobriety test administered by a DRE at the scene. “When he failed the sobriety tests, Mr. Bingley was charged with driving while drug impaired,” a case summary notes.

Bingley admitted to taking two Xanax and smoking marijuana in the 12 hours before he was stopped by police. The DRE decided Bingley’s ability to drive was impaired by marijuana use. A urine test revealed the presence of cannabis, cocaine and Alprazolam.

Bingley was acquitted in an Ontario court, and a summary conviction appeal led to the acquittal being overturned and a new trial being ordered.

There, a second judge ruled that the DRE evidence could be admitted without a voir dire. However, on the voir dire, the judge determined that the DRE evidence was inadmissible, and Bingley was again acquitted.

The Crown’s appeal of that decision will now go to trial.

"Driving while impaired by drugs is a dangerous and, sadly, common activity, prohibited by the Criminal Code," Chief Justice Beverley McLachlin wrote in an explanation of the Supreme Court ruling. "Parliament long ago established a regime to enforce the law against alcohol-impaired driving, with breathalyzer testing and analyst certification at its centre. Enforcing the offence of drug-impaired driving was more elusive."

In her dissenting reasons, however, Justice Andromache Karakatsanis said that the 12-step evaluation used by DREs should be viewed as a tool for investigators, not as “an evidentiary shortcut at trial.”

With files from The Canadian Press