Twenty-second Amendment to the United States Constitution
The amendment prohibits any individual who has been elected president twice from being elected again. Under the amendment, an individual who fills an unexpired presidential term lasting greater than two years is also prohibited from winning election as president more than once. Scholars debate whether the amendment prohibits affected individuals from succeeding to the presidency under any circumstances or whether it only applies to presidential elections.
Twentieth Amendment to the United States Constitution
Section 3 further refines the earlier mentioned Twelfth Amendment provision by declaring that if the president-elect dies before Inauguration Day, the vice president-elect will be sworn in as president on that day and serve for the full four-year term to which that person was elected; it further states that if on Inauguration Day a president-elect has not yet been chosen, or if the president-elect fails to qualify, the vice president-elect would become Acting President on Inauguration Day until a president-elect is chosen or the president-elect qualifies. Section 3 also authorizes Congress to determine who should be acting president if a new president and vice president have not been chosen by Inauguration Day. Acting on this authority, Congress added "failure to qualify" as a possible condition for presidential succession in the Presidential Succession Act of 1947. Previously silent on this point, the lack of guidance nearly caused a constitutional crisis on a couple of occasions: when the House of Representatives seemed unable to break the deadlocked election of 1800 and when Congress seemed unable to resolve the disputed 1876 election.