What is a constitutional amendment?

A constitutional amendment is a formal change to the Constitution made through the procedure laid out in Article V, the only legitimate way to alter the basic rules of American government. Amendments may add new provisions, modify existing ones, or repeal earlier provisions. Once ratified, an amendment carries the same legal weight as the original 1787 text and overrides any conflicting earlier text.

The amendment process has two stages. Proposal requires either a two-thirds vote of both chambers of Congress or a constitutional convention called by Congress at the application of two-thirds of state legislatures. Ratification requires approval by three-fourths of the states, currently 38 of 50, either through their state legislatures or through state conventions specifically called for the purpose. Congress chooses which ratification method applies. The Twenty-First Amendment, which repealed Prohibition in 1933, was the only amendment to be ratified by state conventions; all others have gone through state legislatures.

The Constitution has been amended 27 times since 1791. The first ten amendments, the Bill of Rights, were ratified together as a single package on December 15, 1791, addressing concerns raised during the ratification debates and adding explicit protections for individual liberty. Later amendments addressed specific national issues. The Reconstruction Amendments, ratified between 1865 and 1870, abolished slavery, guaranteed equal protection of the laws, and barred denial of voting rights based on race.

Other notable amendments include the Sixteenth in 1913 authorizing federal income tax, the Seventeenth in 1913 providing direct election of senators, the Nineteenth in 1920 giving women the right to vote, the Twenty-Second in 1951 limiting presidents to two terms, the Twenty-Fourth in 1964 banning poll taxes, the Twenty-Fifth in 1967 setting rules for presidential succession, the Twenty-Sixth in 1971 lowering the voting age to 18, and the Twenty-Seventh in 1992 delaying congressional pay raises.

Six proposed amendments cleared Congress but failed ratification, including the Equal Rights Amendment for women. Thousands more have been proposed and never advanced past Congress. The high bar for ratification ensures that constitutional change requires broad and enduring agreement across regions, parties, and generations rather than the momentary preferences of any majority. Once added, amendments rarely fail. Only one, the Eighteenth, was later repealed.