Exclusive federal powers are powers within a federal system of government that each constituent political unit (such as a state or province) is absolutely or conditionally prohibited from exercising. That is, either a constituent political unit may never exercise these powers, or may only do so with the consent of the federal government.
These powers are contrasted with concurrent powers, which are shared by both the federal government and each constituent political unit.
In American political discourse, states' rights are political powers held for the state governments rather than the federal government according to the United States Constitution, reflecting especially the enumerated powers of Congress and the Tenth Amendment. The enumerated powers that are listed in the Constitution include exclusive federal powers, as well as concurrent powers that are shared with the states, and all of those powers are contrasted with the reserved powers—also called states' rights—that only the states possess. Since the 1940s, the term "states' rights" has often been considered a loaded term, a euphemism, or a dog whistle because of its use in opposition to federally-mandated racial desegregation and, more recently, same-sex marriage and reproductive rights.
Concurrent powers are powers of a federal state that are shared by both the federal government and each constituent political unit, such as a state or province. These powers may be exercised simultaneously within the same territory, in relation to the same body of citizens, and regarding the same subject-matter. Concurrent powers are contrasted with reserved powers (not possessed by the federal government) and with exclusive federal powers (forbidden to be possessed by the states, or requiring federal permission).
In many federations, enumerated federal powers are supreme and so, they may pre-empt a state or provincial law in case of conflict. Concurrent powers can therefore be divided into two kinds: those not generally subject to federal pre-emption, such as the power to tax private citizens, and other concurrent powers.