constitutional amendment
An amendment is a formal revision or addition to the United States Constitution. Under Article V of the U.S. Constitution, there are several methods to propose an amendment. Once an amendment is proposed, it requires the approval of three-fourths of the states to be ratified.
Historically, states have been free to ratify proposed amendments at their leisure for an indefinite period of time. For example, the Twenty-Seventh Amendment was not ratified by the necessary number of states until over two hundred years after it was proposed. Modern amendment proposals tend to include a seven-year time limit for states to ratify an amendment. For this reason, the Equal Rights Amendment has not become law despite achieving ratification by three-fourths of the states. There are currently twenty-seven amendments to the United States Constitution. The first ten amendments are known as the Bill of Rights.
[Last reviewed in May of 2026 by the Wex Definitions Team]
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