In the United States (US), state's rights are the political rights and powers the states have in regard to the federal government. State's rights are guaranteed in the Tenth Amendment to the US Constitution, which states that "the powers not delegated to the United States by the Constitution, nor prohibited by it to the States, are reserved to the States respectively, or to the people." The term also refers to the political argument that the constitution limits the powers of the federal government to those specifically listed in the constitution, and extends the powers of the states to cover all other areas.
The US Supreme Court first discussed the issue of state's rights in McCullough v. Maryland. This case came about when the federal government established a federal bank in Maryland, which was exempt from state taxes by law. Maryland attempted to enforce its state laws by taxing the bank. The Supreme Court ruled that federal laws generally override state laws; therefore, Maryland could not use its state laws to tax a bank that by federal law was tax-exempt. After this decision, legal arguments focused on the scope of state power, particularly whether states possess any powers to the exclusion of the federal government.
State's rights again came to the forefront during the US Civil War, in which several Southern states seceded from the US in 1861 and formed the Confederate States of America, in part due to conflicting views of state's rights. The Confederacy argued that each of its states possessed the right to pursue fleeing slaves into Northern states where slavery was outlawed in order to capture and return the slaves. Northern states argued that the Southern states' intrusion onto their territory in order to recapture fleeing slaves intruded on their state's rights to outlaw slavery within their boundaries.
In the years following the Civil War, the powers of states have gradually declined and the federal government has taken on an increasing role. The decline began with the passage of the Fourteenth Amendment, which applied procedural due process and most of the provisions of the Bill of Rights to the states. Specifically, the Seventeenth Amendment provided that individual voters, not states, would elect members to the US Senate, eliminating the states' direct role in forming the federal government. Expansion of laws surrounding the Commerce Clause gave the federal government the power to control most areas of national commerce, as well.