What are the limits of the power of the police in searches?

This police power has three important limits (as quoted in Caslake at para. 14, quoting Cloutier v. Langlois, 1990 CanLII 122 (SCC), [1990] 1 S.C.R. 158): 1. This power does not impose a duty. The police have some discretion in conducting the search. Where they are satisfied that the law can be effectively and safely applied without a search, the police may see fit not to conduct a search. They must be in a position to assess the circumstances of each case so as to determine whether a search meets the underlying objectives. 2. The search must be for a valid objective in pursuit of the ends of criminal justice, such as the discovery of an object that may be a threat to the safety of the police, the accused or the public, or that may facilitate escape or act as evidence against the accused. The purpose of the search must not be unrelated to the objectives of the proper administration of justice, which would be the case for example if the purpose of the search was to intimidate, ridicule or pressure the accused in order to obtain admissions. 3. The search must not be conducted in an abusive fashion and in particular, the use of physical or psychological constraint should be proportionate to the objectives sought and the other circumstances of the situation.