The case of R. v. Logue, 2016 ONCA 659 provides a useful summary of the type of evidence that a Court can look to in order to find that a driver was impaired:
Four considerations taken together reasonably supported the trial judge’s finding that the appellant’s ability to operate a motor vehicle was impaired by alcohol: first his evidence of alcohol consumption; second the accident was unexplained; third the appellant’s obstructive behaviour in the ambulance; and fourth the statutory inference available from the appellant’s refusal to give a breath sample.