Twenty-second Amendment to the United States Constitution
As worded, the primary focus of the 22nd Amendment is on limiting individuals twice elected to the presidency from being elected again. Due to this, several issues could be raised regarding the amendment's meaning and application, especially in relation to the 12th Amendment, ratified in 1804, which states, "But no person constitutionally ineligible to the office of President shall be eligible to that of Vice-President of the United States". While it is clear that under the 12th Amendment the original constitutional qualifications of age, citizenship, and residency apply to both the president and vice president, it is unclear whether someone who is ineligible to be elected president could be elected vice president. Because of this apparent ambiguity, there may be a loophole in the 22nd Amendment whereby a two-term former-president could be elected vice president and then succeed to the presidency as a result of the incumbent's death, resignation, or removal from office (or even succeed to the presidency from some other stated office in the presidential line of succession).
President of the United States
Some presidents have had significant careers after leaving office. Prominent examples include William Howard Taft's tenure as Chief Justice of the United States and Herbert Hoover's work on government reorganization after World War II. Grover Cleveland, whose bid for reelection failed in 1888, was elected president again four years later in 1892. Two former presidents served in Congress after leaving the White House: John Quincy Adams was elected to the House of Representatives, serving there for seventeen years, and Andrew Johnson returned to the Senate in 1875. John Tyler served in the provisional Congress of the Confederate States during the Civil War and was elected to the Confederate House of Representatives, but died before that body first met.