Recent debates about immigration have focused overwhelmingly on unauthorized migration and the respective roles of the federal and state governments in enforcing immigration law. But that emphasis in law and theory has obscured a critical civil rights question of our time: what measure of equality is due to those with the opportunity to abide by the rules of entry, who are now lawfully present within the United States? Although the United States Supreme Court recognized decades ago that lawfully present migrants are a discrete and insular minority entitled to heightened judicial protection under the Equal Protection Clause of the Fourteenth Amendment, in recent years, a body of little-analyzed federal and state court decisions has eroded that longstanding precedent, elevating deference to the federal government’s power to set immigration policy over a previously established constitutional commitment to immigrants’ equal treatment by the states. This Article critically explores this development and argues that although federalism may legitimately serve as a lens through which to gauge arbitrary discrimination, federalism principles should not stealthily serve as a preemption-like doctrine beneath the surface in equal protection cases. To reign in federalism’s potentially disruptive impact on immigrants’ rights, this Article argues that courts should consider federalism principles only as an interpretative tool in equal protection cases involving migrants and recommit to immigrants’ long settled right to equal treatment by the states.