From 1819 to 1914, governments in northern North America struggled to deal with crime and criminals migrating across the Canadian-American border. Limited by the power of territorial sovereignty, officials were unable to simply retrieve fugitives and refugees from foreign territory. Borderline Crime examines how law reacted to the challenge of the border in British North America and post-Confederation Canada. For nearly a century, officials ranging from high court judges to local police officers embraced the ethos of transnational enforcement of criminal law. By focusing on common criminals, escaped slaves, and political refugees, Miller reveals a period of legal genesis where both formal and informal legal regimes were established across northern North America and around the world to extradite and abduct fugitives. Miller also reveals how the law remained confused, amorphous, and often ineffectual at confronting the threat of the border to the rule of law. This engrossing history will be of interest to legal, political, and intellectual historians alike.