How have courts interpreted s. 8 of the Charter on searches and seizures?

23. One further general point must be made, and that is that if the privacy of the individual is to be protected, we cannot afford to wait to vindicate it only after it has been violated. This is inherent in the notion of being secure against unreasonable searches and seizures. Invasions of privacy must be prevented, and where privacy is outweighed by other societal claims, there must be clear rules setting forth the conditions in which it can be violated. This is especially true of law enforcement, which involves the freedom of the subject. Here again, Dickson J. made this clear in Hunter v. Southam Inc. After repeating that the purpose of s. 8 of the Charter was to protect individuals against unjustified state intrusion, he continued at p. 160: That purpose requires a means of preventing unjustified searches before they happen, not simply of determining, after the fact, whether they ought to have occurred in the first place. This, in my view, can only be accomplished by a system of prior authorization, not one of subsequent validation. [Emphasis in original.] He was there speaking of searches, but as I will endeavour to show, the statement applies equally to seizures.