The accused was charged with operating a vehicle with a blood alcohol level exceeding the legal limit.
At trial, he testified he had consumed two large beers, and a defence expert testified that based on this consumption, his blood alcohol level should have been much lower than the breathalyzer results.
The trial judge rejected the accused's testimony as not credible and therefore rejected the expert opinion based on it, convicting the accused.
The Superior Court and Court of Appeal overturned the conviction.
The Supreme Court of Canada allowed the Crown's appeal and restored the conviction, holding that an expert opinion based on rejected testimony cannot constitute 'evidence to the contrary' to rebut the statutory presumption of accuracy of breathalyzer results.
