The current moment of globalization is witnessing an extraordinary movement of people, legitimate and illegitimate, across national and international borders. These movements are exposing the porosity of borders, the transnational reality of migrant existence, and the contingent foundations of international law. This chapter examines how international law's current engagement with difference in the context of cross-border movements reflects the insecurity and instability that is being produced by the disruptive emergence of this new global subject, which is challenging the very identity of the sovereign state and the sovereign citizen. It discusses how recent legal responses to cross-border movements have been partly informed by the "War on Terror," which has converged with the xenophobic discourse of the conservative right and turned it into a hostile, antagonistic fear of the "Other" who is threatening the security of the nation. Cross-border movements must be addressed against the broader canvas of transnationalism.