Principles généraux relatifs à la conduite facultés affaiblies

R. c. Andrews (1996) 104 C.C.C. (3d) 392

In my view, the following general principles emerge in an impaired driving charge:

(1) the onus of proof that the ability to drive is impaired to some degree by alcohol or a drug is proof beyond a reasonable doubt;

(2) there must be impairment of the ability to drive of the individual;

(3) that the impairment of the ability to drive must be caused by the consumption of alcohol or a drug;

(4) that the impairment of the ability to drive by alcohol or drugs need not be to a marked degree; and

(5) proof can take many forms. Where it is necessary to prove impairment of ability to drive by observation of the accused and his conduct, those observations
must indicate behaviour that deviates from normal behaviour to a degree that the required onus of proof be met. To that extent the degree of deviation from
normal conduct is a useful tool in the appropriate circumstances to utilize in assessing the evidence and arriving at the required standard of proof that the
ability to drive is actually impaired.