Legal Framework and Criminal Law
The division of power
Criminal law is federal: only Parliament can create criminal offences (Constitution Act, 1867, s.91(27)). Provinces create regulatory offences - licensing breaches, trespass, liquor, traffic, fire-code violations. Mixing the two is a classic exam trap.
Offence structure
Every offence needs actus reus (the prohibited act or omission) plus mens rea (the guilty mental state), committed by an identified person, at a stated time and place. Offences are summary conviction, indictable, or hybrid (the Crown elects the procedure).
Arrest powers you actually have
Criminal Code s.494: any person may arrest without warrant (a) someone who, on reasonable grounds, they believe has committed an indictable offence, or (b) someone found committing a criminal offence - any criminal offence, even a summary one. Section 494(2) lets an owner or lawful possessor arrest for a criminal offence committed on or in relation to the property. Under s.494(3) the arrested person must be delivered to a peace officer forthwith. Tell the person they are under arrest and why, use only necessary force, and do not delay to question them.
Force and self-defence
s.25 (acts authorized by law), s.26 (excessive force is itself criminal), s.27 (force to prevent an offence), s.34 (self-defence: reasonable belief of force or threat, defensive purpose, and a reasonable response), s.35 (defence of property). The Charter (ss.9, 10) governs state action; private guards are regulated primarily by the Code, the common law and their employer's policy.
Trap: treating 'reasonable suspicion' as enough where the Code requires belief of an indictable offence; arresting for a provincial offence or a policy breach; assuming guards 'lay charges' (the Crown decides); assuming an arrest includes a right to search.
Rule of thumb: grounds to arrest are not grounds to search - and the clock on 'forthwith' starts the moment the cuffs go on.