By way of reply, I would like to refer to the interception of private communications. This is referred to in sections 181 and following of the Criminal Code. It is surprising to see that a whole section of the Criminal Code deals exclusively with interceptions of private communications. That is a good indication of how important they are.
At the beginning of this part, it states that listening illegally to private communications is a crime and an invasion of privacy. It then strikes a balance by referring to the conditions under which wiretapping can, in some cases, be permitted. It talks here about a warrant to which certain conditions are attached and the need to report to a judge.
The fact that, under the Criminal Code, a judge is the one to issue a search warrant is an example of a specific rule which ultimately reassures police officers. They feel reassured at the idea of remaining within these rules when they take initiatives. Otherwise, our society's appreciation for the law could be diminished. Abuses would then be entirely possible.