British imperial history is replete with examples of declarations of independence, often accompanied by violent uprisings or civil conflict. One of the fundamental documents of Canadian independence was also a declaration, albeit of a different character and issued under very different circumstances. In the early 20th century, the Dominions (at the time comprising of the self-governing colonies of Australia, Canada, the Irish Free State, Newfoundland, New Zealand and South Africa) began to increasingly assert their independence from British control. For Canada, the journey towards full independence was a gradual process, brought about in part by the Balfour Declaration in 1926 and which culminated in the adoption of the Statute of Westminster five years later. Today, the Statute of Westminster remains an important milestone in Canadian constitutional history.
Although Canada was a self-governing entity following Confederation in 1867, the Imperial Parliament retained the power to legislate in respect of colonial matters. Canada was also part of a single, indivisible Crown, meaning it remained subordinate to the foreign policy of Great Britain. So, when Great Britain declared war on Germany in 1914, the rest of its Dominions were automatically committed to the war effort. But on the battlegrounds of Ypres, Passchendaele and Vimy Ridge, among many others, the separate and extensive contribution of the Canadian military corps was recognized, which accelerated the process towards greater political and legal autonomy. When the First World War ended with the signing of the Treaty of Paris, Canada signed the Treaty in its own right, and became a founding member of the League of Nations in 1919.
And so Canada began to increasingly assert its position on the international stage. In 1918, the Halibut Treaty was signed between Canada and the United States without Great Britain as a counterparty, an act which was symbolic of Canada's growing separation from imperial diplomatic authority. Further on, in 1922 Canadian Prime Minister William Lyon Mackenzie King sent a non-committal response to a British request for military support in the Chanak Affair by indicating that the Canadian Parliament would need to decide on the country's involvement in the conflict.
Notwithstanding this progress, our legal position continued to reflect imperial parliamentary supremacy. At common law and as reflected in the Colonial Laws Validity Act 1865 (28 & 29 Vict. c. 63)...