The vow's roots lie in the oath of allegiance taken in the United Kingdom, the modern form of which was implemented in 1689 by King William II and III and Queen Mary II and was inherited by and used in Canada prior to 1947. With the enactment of the Citizenship Act that year, the Canadian Oath of Citizenship was established. Proposals for modification of the oath have surfaced from time to time, including removing references to the sovereign, adding loyalty to societal principles, and/or adding specific mention to Canada. However, it is maintained within Canada's legal system "that the oath to the Queen is in fact an oath to a domestic institution that represents egalitarian governance and the rule of law". Consequently, it has only been modified once, in 1977.