R v Mann

Mann recognised, for the first time at the SCC, a common-law power to detain for investigative purposes short of arrest, and an associated limited search power for officer safety. Reasonable suspicion is the threshold.

Police investigating a recent break-in stopped a man matching the suspect description near the scene. They patted him down for safety and felt a soft object in his pocket. The officer reached in and pulled out a bag of marijuana. Mann was charged with possession for the purpose of trafficking.

(1) Does Canadian common law recognise an investigative detention power? (2) If so, may police search incident to that detention? (3) Was the search lawful here?

Yes to (1) and (2), with limits. The search exceeded its scope on the facts; the marijuana was excluded.

Police may detain individuals for investigative purposes where there are reasonable grounds to suspect, in light of all the circumstances, that a clear nexus exists between the individual and a recent or ongoing criminal offence. Where officer safety reasonably requires it, a protective pat-down may follow. The search must be confined to identifying weapons.

Iacobucci J held that the Waterfield test, adopted in Dedman, supports a limited investigative-detention power. The detention must be reasonably necessary considering the duty being carried out, balanced against the liberty interest at stake. The search power is for safety only — going further requires arrest grounds. Reaching into the pocket exceeded the safety rationale.

Created a workable framework that police use daily. Subsequent cases (Clayton, MacDonald, Le) refine when investigative detention is justified and how the line with arbitrary detention is policed.

R v Mann, 2004 SCC 52, [2004] 3 SCR 59.

McLachlin CJ, Iacobucci J, Major J, Bastarache J, Binnie J, LeBel J, Deschamps J