On May 15, 1919, 24,000 organized and unorganized workers in Winnipeg walked off the job. Another 6,000 would soon join them. It was the start of the largest strike in Canadian history, and political leaders at all levels were quick to act. Parliament amended the Immigration Act so British-born immigrants could be deported, and expanded the definition of sedition. In a 1969 CBC Radio documentary commemorating the strike, lawyer Jim Walker talks about Ottawa's new laws.
h/t to Nag on the Lake who beat me to it.