This Essay addresses federalism objections to section 3 of the Defense of Marriage Act (DOMA). Ordinarily, the federal government accepts states’ determinations of what couples are validly married. Section 3 of DOMA, however, fashions a broad exception for same-sex couples, who are definitionally deemed not to be in “marriages.” In addition to equal protection and full faith and credit challenges to DOMA, litigants have made constitutional federalism arguments. In Massachusetts v. United
States Department of Health and Human Services, the federal trial court accepted one such argument, though in a form that might be read to categorically deny the federal government authority over marriage. This Essay critiques such categorical federalism arguments, as well as the district court’s specific doctrinal argument, and offers a more nuanced, uncategorical federalism argument against DOMA section 3 based on existing constitutional precedents, an argument that relies on a confluence of factors to conclude that this provision of federal law is unconstitutional.