Ratification also has two possible methods. Three-fourths of the states must approve through their legislatures or through state ratifying conventions, with Congress selecting the method. State legislatures have ratified every amendment except the Twenty-first, for which Congress chose state conventions. The president does not sign, veto, propose in a formal Article V capacity, or ratify an amendment. A president may advocate a change politically, but the constitutional thresholds belong to Congress or a proposing convention and to the states.

The supermajorities make amendment deliberately difficult. A temporary national majority should not be able to rewrite the nation's fundamental law as easily as it passes an ordinary statute. Successful amendments normally require support that crosses institutions, states, regions, and election cycles. Difficulty does not make the Constitution unchangeable: amendments have reconstructed citizenship, expanded voting rights, altered elections, authorized an income tax, and changed presidential tenure. Article V also protects equal state suffrage in the Senate from amendment without the affected state's consent. Congress may place a reasonable ratification deadline in the proposing resolution, as it has for many modern proposals.

Separate the numbers and stages. Two-thirds is associated with proposal: two-thirds of both houses or applications from two-thirds of state legislatures. Three-fourths is associated with ratification by the states. Congress chooses legislatures or conventions as the ratifying bodies; states do not substitute a national popular referendum. Formal amendment changes the constitutional text and binds every branch as constitutional law. It can supersede an earlier constitutional interpretation, but an ordinary statute, executive order, or court decision cannot be labeled an amendment to avoid Article V.

Video lesson: The Constitution, the Articles, and Federalism: Crash Course US History #8