Federalism conflicts turn on the legal mechanism. Congress can regulate private conduct under an enumerated power and preempt incompatible state rules; it can offer funds with lawful conditions; but it generally cannot require a state legislature to enact a federal program or compel state executive officers to administer one.

Rights create another path. Even where states possess subject-matter authority, the Fourteenth Amendment and valid federal civil-rights law can restrict how that power is exercised. Reserved power is therefore not immunity from the Constitution.

Classify the claim before selecting a doctrine: lack of enumerated power, preemption, coercive spending, commandeering, or violation of an individual right. A state cannot nullify federal law, and the federal government cannot treat states merely as administrative departments. The Constitution preserves both supremacy and a meaningful state role.

Video lesson: Federalism: Crash Course Government and Politics #4