The deep relation between the colonial past and contemporary international law has been convincingly established. Scholars from diverse backgrounds, employing a variety of approaches, have shown the multifaceted ways in which the colonial enterprise occasioned the birth of doctrines and practices that are still in common use. The conference that occasioned this symposium, the last of the project History of International Law: Between Religion and Empire, directed by Martti Koskenniemi, was held in Helsinki in October 2016 and approached the issue of the colonial legacy of international law from the point of view of specific histories. The ‘techniques of empire’ raised at the conference encompassed colonial governance in the broadest sense, looking at practices, norms and normative systems, doctrines and concepts, and events. The case studies making up the articles featured in the symposium treat subjects as diverse as the experiences of colonialism have been, assuming an array of forms. Even so, from the multiplicity of techniques certain patterns and themes emerge.