The National Assembly during the Japanese occupation of the Philippines during the Second World War in the Pacific was created under the 1943 Constitution. With the invasion of the Philippines, the Commonwealth government had gone into exile in the United States. It left behind a skeletal bureaucracy whose officials formed a government under the Japanese Imperial Army. In an attempt to win the loyalty of Filipinos, the Japanese established a nominally independent Republic of the Philippines, with a National Assembly as its legislative body. The Second Philippine Republic was only recognized by the Axis powers.
Prior to 1935, the Philippine Islands, an insular area of the United States had the bicameral Philippine Legislature as its legislative body. The Philippine Legislature was established in 1907 and reorganized in 1916, pursuant to a U.S. federal law known as the Jones Law. The Jones Law provided for a Senate and a House of Representatives, whose membership were elected except for a few, which were appointed by the U.S. Governor-General, without the need for any confirmation. The Governor-General being the chief executive of the territory also exercised the power to veto any of the Philippine Legislature's legislations.
In 1934, Filipino politicians obtained the passage of a Philippine independence law known as the Tydings–McDuffie Act. It was crafted to prepare the Philippines for its eventual independence after a ten-year period. The Tydings–McDuffie Act also enabled them to draft and adopt a constitution, subject to the concurrence of the U.S. President.
In the constitutional convention that followed, a unicameral National Assembly was adopted. This came after the failure of the constitutional convention delegates to agree on the setup of the bicameral system that was favored by the majority. It also set the ceiling on its membership to a maximum of 120, that were to be elected every three years; similar to what the Jones Law had provided. It entitled every province, regardless of its population to have at least one representative. The convention likewise provided for the direct election of representatives from the non-predominantly Christian areas previously appointed by the U.S. Governor-General.
After the 1935 Constitution was ratified, elections were held on September 17, 1935 for the 98 members of the National Assembly; simultaneous with the elections for the Commonwealth President and Vice President. The Philippine Commonwealth was inaugurated on November 15, 1935 and thus the term of the elected officials began. The National Assembly first met officially on November 25, ten days after the Commonwealth government was inaugurated and elected Gil M. Montilla of Negros Occidental as its Speaker. It soon organized itself into 3 commissions and 40 standing committees, when it adopted its rules on December 6.