Federalism

MBE federalism questions usually hide the real issue inside a fact pattern about something else, so your first move is always identify which side is acting. If Congress acts, ask whether an enumerated power authorizes it (the answer can’t be “general welfare” as a standalone power — that phrase only states the purpose of the taxing-and-spending power, not a freestanding right to regulate). If a state acts, presume the police power supplies authority and hunt for a federal limit: preemption, the dormant Commerce Clause, or an individual right. The answer usually turns on a default rule — states get the benefit of the doubt on power, the federal government on supremacy.

The classic trap conflates commerce power (Congress’s affirmative authority to regulate) with anti-commandeering (a structural limit barring Congress from ordering states to legislate or enforce). Congress may reach states through laws of general applicability and may attach strings to spending (the South Dakota v. Dole conditions), but it may not commandeer. Don’t confuse preemption (federal law displacing state law) with commandeering (federal law conscripting state machinery to do federal work).