Canadian criminal law is a branch of public law specifically addressing criminal offenses and their corresponding penalties. A criminal offense is fundamentally defined as an anti-social act that violates an individual's duty to society; therefore, the law mandates that such acts be punished.
Canadian criminal law is based on English criminal law. This system was initially composed of customs and common law, which subsequently expanded through the interpretations of generations of judges.
Under the Constitution Act of 1867, the Parliament of Canada has exclusive legislative authority over criminal law. This power includes defining procedures within criminal law, but does not include the organization of criminal courts. Provinces may legislate on law enforcement, including the organization, maintenance, and composition of provincial courts. The Parliament of Canada may also establish courts for the better administration of the laws of Canada.
In the early days of the Canadian Confederation, each colony had its own criminal laws. In 1869, to establish a system applicable nationwide, Parliament passed a series of statutes specifically addressing certain criminal acts and their trial procedures. Most notable among these was the Criminal Procedure Act, while other statutes dealt with summary convictions and trials, the powers and jurisdiction of judges, and procedures for dealing with juvenile offenders.