Simultaneous substitution

Simultaneous substitution, in Canadian broadcasting, is the practice by which cable companies substitute the local Canadian signal over a non-Canadian signal, when two or more stations are airing the same programming at the same time.

Although sometimes controversial, this practice is required by the Canadian Radio-television and Telecommunications Commission as a way to protect the broadcast rights and commercial revenues of Canadian television broadcasters, by ensuring that the Canadian commercials are seen by all viewers of the program.