Abstract: Michael Walzer and David Miller defend the authority of democratic states to determine who will be allowed entry and membership. In support of this view they have claimed that the domestic solidarity necessary for social justice is threatened by the unregulated influx of outsiders. This empirical thesis proves to be false when applied to the United States, where heavy Latino and Latina immigration is more likely to increase civic solidarity than to diminish it. Seen in this light, the positions of Jürgen Habermas and Carol Gould, giving human rights priority over democratic sovereignty in decisions about membership, cannot be criticized as utopian. Liberal philosophers can also defend open borders as a way to give oppressed peoples representation inside powerful countries where state decisions often threaten access to essential resources and basic freedoms in their home countries.