The Letters Patent, 1947 (more formally, the Letters Patent Constituting the Office of Governor General and Commander-in-Chief of Canada) are a legal instrument introduced by King George VI, which came into effect on 1 October 1947 and continue to, along with parts of the Constitution Act, 1867, constitute the Office of the Governor General. These letters served to expand the role and powers of the governor general in exercising the Royal Prerogative, allowing the governor general to carry out an increased number of the King's duties in "exceptional circumstances". While the letters patent allow the governor general to use most of the "powers and authorities" lawfully belonging to the Canadian sovereign, this permission can be revoked, altered, or amended by the sovereign at any time and t