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.
Joseph Estrada
Joseph Estrada stated in interviews that he would be willing to run for the opposition in the event that they are unable to unite behind a single candidate. Fr. Joaquin Bernas and Christian Monsod, members of the constitutional commission that drafted the 1987 Constitution, stated that the constitution clearly prohibits any elected president from seeking a second term at any point in time. Romulo Macalintal, election counsel of President Arroyo, clarified that the constitutional ban doesn't prevent Estrada from attaining the presidency in the event that he were to be elevated from the vice-presidency, for example.
However, Rufus Rodriquez, one of Estrada's lawyers, claims that the former president is within his rights to do so because the prohibition banning re-election only applies to the incumbent president.