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.
List of Presidents of the United States by time in office
William Henry Harrison spent the shortest time in office, and Franklin D. Roosevelt spent the longest. Roosevelt is the only president to have served more than two terms. Following ratification of the Twenty-second Amendment in 1951, presidents—beginning with Dwight D. Eisenhower—have been ineligible for election to a third term or for election to a second full term after serving more than two years of a term to which some other person was elected president. The amendment contained a grandfather clause that explicitly exempted the incumbent president, then Harry S. Truman, from the new term limitations, which first applied to Dwight D. Eisenhower.