The Twelfth Amendment (Amendment XII) to the United States Constitution provides the procedure for electing the President and Vice President. It replaced the procedure provided in Article II, Section 1, Clause 3, by which the Electoral College originally functioned. The amendment was proposed by the Congress on December 9, 1803, and was ratified by the requisite three-fourths of state legislatures on June 15, 1804. The new rules took effect for the 1804 presidential election and have governed all subsequent presidential elections.
