National immigration policy meets the realities of unauthorized immigration at the local level, often in ways undesired by residents, as exemplified by the dramatic rise of local anti-immigrant legislation in US states and municipalities. Scholars have studied why some states and municipalities, but not others, engage in immigration policy making. Such research is not designed, however, to evaluate how the basic structure of US government facilitates and shapes local protest. To probe that issue, we compare Chiapas, Mexico and Arizona, USA, both peripheral areas significantly affected by unauthorized immigration and national policies designed to control it. We find that the open texture of US federalism facilitates local activism, while Mexico's more centralized government does not. Activists within both states are similar, however, in deploying law creatively to critique national policy, a reminder of the growing worldwide significance of legal pluralism and legal consciousness in the politics of protest.