The current debate over the meaning of American federalism bears a striking resemblance to our founding struggle over states' rights. One stage where federalism continues to play out is the regulation of aliens and immigration. For most of our first century, immigration control was a state prerogative. But by the late nineteenth century, the Supreme Court equated immigration with foreign policy, thereby recognizing plenary and exclusive federal authority. This exclusivity operates to negate state power by both standard preemption doctrine and constitutional preclusion. In particular, preclusion forecloses state immigration laws even where Congress is silent since states have never possessed (nor do they "retain") power over foreign affairs.
Despite this proscription, states continue to regulate aliens and immigration, often in response to xenophobic and nativist pressures. The best modern example is California's Proposition 187, which was designed to fill perceived gaps in federal immigration policy. Yet, no matter how urgent immigration laws are thought to be, they are beyond state power. This article describes the history and practice of state immigration laws and explores their constitutionality.
State Immigration Laws and Federal Supremacy,
22 Hastings Const. L.Q. 939
Available at: https://repository.uchastings.edu/hastings_constitutional_law_quaterly/vol22/iss4/3