In 1999 Germany passed a major reform of its citizenship law, shaking off, however incompletely, its a century-old understanding of the German nation as based in blood. We examine this reform and especially the extended struggle that preceded it in order to better understand how international human rights norms come to play a role in the domestic politics of liberal democracies. Drawing on work in political sociology, international relations, and political theory, we argue that the power of human rights norms should not be measured in terms of their ability to coerce states into action, but rather as a political resource, a means by which the excluded and their advocates can confront existing legal arrangements and cultural understandings. In contrast to scholars who have attempted to trace the influence of global norms from the top down, we focus on moments of contentious politics in which claims are advanced through the language of human rights. We show that these moments played an important and hitherto underappreciated part in driving the extension of German citizenship to former "guest workers" and their descendants.