The Padlock Law (officially called "Act to protect the Province Against Communistic Propaganda") (QcFr: "La loi du cadenas" / "Loi protégeant la province contre la propagande communiste", 1 George VI Ch. 11) was an Act of the province of Quebec, passed on March 24, 1937 by the Union Nationale government of Maurice Duplessis, that was intended to prevent the dissemination of communist propaganda.
The Act prohibited anyone to "use [a house] or allow any person to make use of it to propagate communism or bolshevism by any means whatsoever" as well as the printing, publishing or distributing of "any newspaper, periodical, pamphlet, circular, document or writing, propagating Communism or Bolshevism." A violation of the Act subjected such property to being ordered closed by the Attorney General - "padlocked" - against any use whatsoever for a period of up to one year, and any person found guilty of involvement in prohibited media activities could be incarcerated for three to thirteen months.
The law was ill-defined, denied the presumption of innocence, and clearly denied the right of freedom of speech to individuals. There were also concerns that the law would be used in order to arrest individual activists from international trade unions. Two union leaders were nearly arrested in that period. While it was applied frequently against a range of radical leftist groups, allegations that Duplessis used it against political opponents, including the left-wing United Jewish Peoples' Order in 1950, reports that it was used against the Jehovah's Witnesses are incorrect: the authorities typically used municipal by-laws, such as the one featured in Saumur v. The City of Quebec.
The federal government under Liberal Prime Minister William Lyon Mackenzie King could have used its powers of disallowance and reservation to nullify the Padlock Law, as it had done to overturn equally controversial laws that had been passed by Alberta's Social Credit government around the same time. However, King chose not to intervene in Quebec. The most likely reason is that King did not want to alienate the rural support base of the Union Nationale, which was continuing to support the Liberals federally.
- Rouillard, Jacques (1989). Le syndicalisme québécois : Deux siècles d'histoire. Montréal: Éditions Boréal, at page 68. ISBN 2-89052-243-1