The principal case for all federal regulation of broadcasting space is, of course, the radio reference of 1932. In that, the court relied upon the provisions of subsection 92(10) of the Constitution Act to find that, in transmitting radio waves, they necessarily exceeded provincial boundaries and, therefore, could only be effectively regulated at the federal level. The key is that, in order to be regulated by the federal government, the “undertaking”, as the Constitution uses the word, has to be one that has the facilities to exceed provincial limitations and provincial boundaries.
On May 31st, 2022. See this statement in context.