Impaired Driving

Proof of Impairment or Impaired Driving

The Criminal Code of Canada does not prescribe any special test for determining impairment, or impaired driving such as a "marked departure" from normal behavior. If the evidence of the police officer or witness describes any level of impairment ranging from slight to great, the offence of impaired driving may be made out.

It cannot be assumed, however, that where a persons"s functional ability is affected in some respects by the consumption of alcohol, his ability to drive is also automatically impaired.

Where the proof of impaired driving consists of observations of conduct, in most cases if the conduct is a slight departure from normal conduct, it would be unsafe to conclude the the accused's ability was impaired by alcohol.

An accused may be conviction of this offence although his impaired driving condition is due partly to fatigue and partly to the consumption of alcohol

The court is not entitled to take judicial notice that at a certain blood-alcohol level the accused's ability to driver would have been impaired

On a charge of impaired driving the trial judge can take into account the "Certificate of Analysis" of a police breathalyzer technicians evidence that prior to being stopped the accused most likely had consumed alcohol. In doing so the judge was not need to draw on any technical or special knowledge of the impaired driving.