The most prominent issues during Makasiar's tenure on the Court concerned the validity of the acts of the martial law regime began by Marcos in 1972. On those issues, Makasiar had been described as a loyal ally of Marcos and a consistent supporter of the President's New Society policies. He was among the Justices who voted to affirm the validity of the 1973 Constitution in the seminal case of "Javellana v. Executive Secretary", 50 SCRA 33 (1973). More prominently, in "Aquino v. COMELEC", 62 SCRA 33 (1975), Makasiar wrote for the Court as it denied petitions for prohibition which maintained that Marcos, whose original term as President expired 2 years earlier, held no legal office nor lawful authority. Relying on "Javellana" and "Aquino v. Ponce-Enrile" (which affirmed the validity of the 1972 proclamation of martial law), Makasiar wrote that Marcos was the de jure incumbent President of the Philippines.