Tonight on the National, Rex Murphy twigged me to this story.
Back in the early 90s I worked briefly as a security guard. During my training, we were explicitly told to avoid making citizen arrests or otherwise detaining suspects that were on the premises we were "guarding". Why? Because we could be charged for forcible confinement, or at worse kidnapping.
To the point we were informed that if we were patrolling a mall, and we saw a shoplifting suspect, we were not to touch them. Even just holding up our hand as they ran toward us, if we wound up putting our palm on their chest, we were risking charges of assault.
Our sole job was to record and observe, and to pass those observations to police officers who were responsible for any arrests. Nuts huh? The badge on my uniform said "security guard" and we were employed as such. But any attempts to "guard" anything, meant risking charges and possible conviction for assault, forcible confinement and whatever charges the perps lawyers could dream up.
So now you know. Under Canadian law, though you have the powers of "citizens arrest" you have to do it without any physical contact with the suspect at all.
Or you'll face charges just like in the story linked above.