Many will recall the photo of Arizona’s governor, Jan Brewer, standing on the tarmac and wagging her finger in the face of President Obama, just after Air Force One touched down in Arizona this past January. But when it comes to S.B. 1070-style laws, it isn’t about Brewer vs. Obama. It is about Brewer vs. America’s founders.

Our federalist system provides for state innovation in many areas, but not immigration.

The architects of our Constitution, like James Madison and Alexander Hamilton, made it absolutely clear that the federal government has the exclusive power to regulate immigration, and to consider the foreign policy implications of how we treat noncitizens within our borders. While our federalist system provides for state diversity and innovation in many key areas, the Constitution unmistakably vests the power over immigration and naturalization, and related issues like border security and foreign relations, in the federal government. Arizona’s decision to pursue a single-minded, aggressive, nondiscretionary policy of “attrition through enforcement” conflicts with the complex balancing act that the Constitution, Supreme Court precedent and specific congressional enactments have delegated to the executive branch.

State and local governments, businesses located within the states and localities, and residents, of course, experience both the benefits and burdens of unauthorized migrants up close. These stakeholders’ perspectives are incredibly important to the national conversation on immigration reform. Congress has specifically allowed for state cooperation with federal immigration enforcement in certain areas — provided, however, that such state and local officers have the sufficient training and supervision to enforce complex immigration regulations — and the Supreme Court has upheld the authority of states to regulate in areas of traditional local concern, such as business licensing, that may affect noncitizens. But however important the voices of state and local officials in the debate, the Constitution makes clear that, when it comes to actually setting immigration law and policy, the United States must speak with one voice: the federal government’s.