During World War I the federal Crown's power was extended with the introduction of income taxes and passage of the War Measures Act, the scope of which was determined by several court cases. The constitution's restrictions of parliamentary power were affirmed in 1919 when, in the Initiatives and Referendums Reference, a Manitoba act providing for direct legislation by way of initiatives and referendums was ruled unconstitutional by the Privy Council on the grounds that a provincial viceroy (even one advised by responsible ministers) could not permit "the abrogation of any power which the Crown possesses through a person directly representing it". Social and technological changes also worked their way into constitutional authority; the "Radio Reference" found that federal jurisdiction extended to broadcasting, and the "Aeronautics Reference" found the same for aeronautics.