The appellant was arrested by Ontario Provincial Police officers while walking to a counter-protest flag rally, having committed no offence and presenting no threat of violence.
The police relied on a purported common law power to arrest someone acting lawfully in order to prevent an apprehended breach of the peace by others.
Applying the ancillary powers doctrine, the Court held that no such common law power exists: the power is not reasonably necessary because statutory arrest powers already address situations where individuals resist or obstruct officers taking less intrusive measures, and effectiveness of a police action alone cannot justify an arrest if less intrusive means were available.
The Court restored the trial judge's award of damages for battery, wrongful arrest and false imprisonment, and found no new trial was warranted on the issue of excessive force because the arrest itself was unlawful.