Amendment to the U.S. Constitution that separated the vice presidential and presidential voting in the electoral college, originally formalized in Article II of the Constitution.
The Twelfth Amendment altered the stipulation in Article II of the U.S. Constitution that each elector cast two votes for president, and the candidate receiving the second highest number of votes become vice president. The Twelfth Amendment created separate electoral college votes for president and vice president to ensure that the two offices are held by members of the same party. According to the Twelfth Amendment, when no majority exists, the House of Representatives chooses the president from the three candidates with the highest number of popular votes.
The Twelfth Amendment resulted from the emergence of the two-party system
Two major Supreme Court cases regarding the Twelfth Amendment are McPherson v. Blacker
Constitutional amendment process