In chapter 5, I describe how participants in the 1916 debates used the law of nations as it existed at the time, and the dominion and constitutional law of the British Empire to deliberate the justifications for war and for conscription. The languages of these debates included, for example, arguments about the preservation of White Australia, about the need to protect Australians’ civil liberties, and about the unequal claims made on the different classes of Australian society as a result of the First World War. The persuasiveness of uses of international legal language in 1916 depended on speakers’ abilities to navigate the complications of Australia’s colonial nationalism. Speakers made sophisticated arguments about the duties of the Dominion of Australia to the British Empire on the one hand, and to its own emerging nationhood on the other.