Combines Investigation Act

The Combines Investigation Act, 1923 (French: Loi relative aux enquêtes sur les coalitions), was a Canadian Act of Parliament that regulated certain anti-competitive corporate business practices. It prohibited monopolies, misleading advertising, bid-rigging, price fixing, and other means of limiting competition.

First introduced in 1910, the original legislation was repealed before an updated version was enacted in 1923 by MacKenzie King; the Act was also amended in 1969 by the Criminal Law Amendment Act, 1968–69.

It was a rather notorious piece of legislation in Canadian constitutional law for the powers it granted to non-police officers to enter private premises without a judicially-issued search warrant and seize evidence that they suspected were in relation to a violation of the Act. This led to the Supreme Court decision in Hunter v Southam Inc where provisions of the Act were held to be inoperative in light of the recently enacted Canadian Charter of Rights and Freedoms' section 8 protection against unreasonable search and seizure. The Act was repealed in July 1986 and replaced with the Competition Act.

The Combines Investigation Act was the eventual successor to the Anti-Combines Act, passed on 2 May 1889 as the first antitrust statute in the industrial world.