Printz v. United States (1997) held that Congress cannot force state sheriffs to run federal background checks. Over time, states of both parties used the anti-commandeering principle to refuse cooperation with federal law, from sanctuary cities to cannabis legalization to Second Amendment sanctuaries. The episode traces how a narrow ruling became a broad tool.
Scholars debate whether sanctuary laws interfere with federal authority under the Supremacy Clause; lower courts have split and the Supreme Court has not resolved it. The Murphy v. NCAA extension was controversial, and the use of Spending Clause conditions is itself argued to be a form of coercion.



