Drug test slower, not as reliable as alcohol breath test

Testing to see who’s too stoned to drive is a cumbersome system that results in few convictions, says a law professor who has studied cannabis impairment.

The federal Liberals have tabled legislation to legalize marijuana while having severe penalties for drug-impaired driving. But Robert Solomon of Western University says that enforcement of laws involving pot and driving can be difficult.

First, forget about a handy roadside breath test like the test for alcohol, he advises.

“There is some preliminary research indicating that a breath test can be developed for cannabis. It’s slow, expensive and not yet reliable,” he said. “So we’re a long way from a breath test for cannabis ... (despite) some promoters out there who have been touting miraculous, easy, cheap” breath tests.

That leaves three options, Solomon says: Today’s version: A police officer pulls over a driver and begins with a field sobriety test. These are simple tasks. For instance: Can you walk in a straight line? If you fail that, you’re given a breath test, and if this shows that alcohol isn’t your problem, then police can take you away for “drug recognition evaluation,” or DRE.

This is a 12-part test. The first 11 steps deal with physiological aspects — pulse, temperature, signs of needle marks, and some signs of impairment.

The final step, if a driver seems impaired, is to demand a sample of urine, blood or saliva.

“The difficulty is that the request for a sample is at the end of the process,” he said. Cannabis dissipates from the blood quickly, and he says it may take up to two hours to reach the point where a driver actually provides the sample.

“The longer the delay, the more likely that the person is not going to test positive.”

He says it also costs $17,000 to

The longer the delay, the more likely that the person is not going to test positive.

train one officer in this process. The officer has to compile a long list of points in the investigation.

“And the simple fact is that our courts haven’t been very receptive to the DRE evidence.

“We have more people on our roads who are positive for drugs than for alcohol. And yet drugimpaired driving charges constitute two to three per cent of all impaired driving charges.” Option two: Australia and some countries in Western Europe allow police to demand a saliva sample from anyone they pull over, just as they can ask for your licence and ownership papers.

In some jurisdictions, any THC (the active chemical in marijuana) is illegal.

It’s still a two-step press, Solomon said: A roadside test, followed by a second test by a more sophisticated machine, which can be saliva, blood or urine. Option three: Again there’s a roadside saliva test and a second test at the police station or hospital, but this time the driver is charged only if the THC content is above a certain level. That makes this system like our alcohol law: A little drug is all right, but anything over a certain line counts as impairment, no matter how a person is acting.

In California, one law firm that specializes in marijuana impairment cases says police rely on three main “field sobriety tests” to begin the evaluation process. They ask a driver to walk in a straight line; they look for “involuntary jerking of the eye” and they ask the driver to stand on one foot.