The Supreme Court has consistently held that state and local governments don’t have to enforce federal laws or implement federal programs. This is known as the anti-commandeering doctrine.
People have become more aware of this important state power, but a lot of folks still think there has to be a constitutional justification to, as James Madison put it, “refuse to cooperate with officers of the union.” This isn’t true. State and local governments don’t have to have any reason at all other than they don’t want to.
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