Federalism
The system of shared sovereignty in the U.S where power is divided between the federal govt. and state govts.
The powers of the federal govt. are enumerated in Articles I, II and III of the Constitution → creates a system in which both federal and state govts. possess sovereignty and neither can abolish the other

Federal government and US states
Federal govt. has more power?
Gains supremacy under Article VI of the Constitution (federal law overrides state law)
Federal law overrides state law (Arizona v U.S 2012 confirmed federal supremacy over immigration enforcement)
Controls national finances → can influence state policy through funding (Biden’s American Rescue Plan 2021 funded Covid-19 relief)
States cannot negotiate treaties or maintain armed forces (Ukraine aid packages were passed regardless of state opposition 2022-24)
State govts. have more power?
Control key domestic policy areas such as education, policing and elections (e.g. after Dobbs v Jackson, power over abortion laws was returned to the States)
States administer federal elections, allowing them to shape voting rules (e.g. Georgia’s Election Integrity Act 2021 altered voting access)
States draw congressional district boundaries (→ gerrymandering controversies in Texas and California 2024)
States can challenge federal authority in the SC (e.g. Biden v Nebrasksa 2023, red states blocked student loan forgiveness)