What is the law relating to the power of the police to search a person incidental to a lawful arrest?

The law relating to the power of the police to search a person incidental to a lawful arrest, is aptly summarized in the headnote in Cloutier v. Langlois, 1990 CanLII 122 (SCC), [1990] 1 S.C.R. 158 (S.C.C.) as follows: At common law a police officer may carry out a "frisk" search of a person who has been lawfully arrested and the existence of reasonable and probable grounds is not a prerequisite to the existence of such a power. ... The exercise of the power to search is not however unlimited. First, this power does not impose a duty. The police have some discretion and, if satisfied that the law can be effectively and safely applied, they may see fit not to conduct a search. They must also be in a position to assess the circumstances of each case so as to determine whether a search meets the underlying objectives forming the basis of the right to search. Second, as regards these objectives, 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 -- and the purpose of the search must not be unrelated to the objectives of the proper administration of justice. Third, 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. A search which does not meet these objectives could be characterized as unreasonable and unjustified at common law.