The 12th Amendment to the United States Constitution is a brief passage that details the procedure governing the election of the president and vice president. It was ratified by the states in 1805 and modifies the Constitution's Article II.
Many changes are imposed by the 12th Amendment. Electors of the Electoral College are required to distinctly cast one vote each for president and vice president, allowing candidates to run as a ticket. Electors can not vote for members of his or her own state for both offices. Eligibility restrictions that constitutionally apply to candidates for president officially apply to candidates for vice president. The House of Representatives is required to choose between the highest three finishers in the event that no candidate wins a majority of electoral votes. The Senate has the same responsibility concerning Vice Presidential candidates. Finally, the amendment required the vice president to act as the president in the event that none could be decided upon by inauguration day.