New & Notable: Judging impairment does not require "expertise"

Jason Henry was impaired. He was driving. He was convicted of driving while impaired by drug. He appealed that conviction. The appeal was dismissed: 2013 ONSC 1214.


One of the issues on appeal was the trial judge’s reliance on the evidence of some witnesses (non-experts) that Henry was impaired.

It is trite law that lay persons (non-experts) can offer an opinion on the issue of impairment by alcohol: R v Graat, 1982 SCR 819. This same view has been expressed in relation to impairment by drug – that is, that lay persons can provide an opinion that a person appeared impaired by a drug: R v Polturak, 1998 CarswellAlta 145 (CA).

Since the enactment of Bill C-2 and the provisions of the Criminal Code that provide for “drug recognition experts” to perform tests to determine if a person’s ability to operate a motor vehicle is impaired by a drug, some courts have had difficulty with this issue.

Fortunately, in Henry, the court had no difficulty with this issue.  In rejecting Henry’s position that the trial judge erred in relying on the evidence of lay people about his impairment McWatt J (sitting as a summary conviction appeal judge) offered the following:

Third, it was not necessary for the Crown to call expert evidence to prove the appellant was impaired. It has long been an accepted practice that a trial judge is entitled to rely on the evidence of lay people in deciding this issue [Graat]; and that is all the judge did when she relied on the civilian, police and the appellant’s evidence to find that Mr. Henry was driving while his ability to do so was impaired by caffeine [para 6].