However, the First Commonwealth Congress was significant in at least three key respects: First, it brought an end the president's exercise of legislative powers under the wartime emergency act passed by the defunct National Assembly in 1941.

Second, the First Commonwealth Congress gave birth to the two-party system in the Philippines, as the pro-Osmeña and pro-Roxas blocs or factions there eventually became the Nacionalista and Liberal Parties that alternated in power from 1945 until martial law was imposed in 1972.

The patron-client orientation of the two-party system evolved in part from the resource constraints faced by members of the Congress right after the war.

Through the most part of the term of the Second National Assembly (1938–1941), the First Congress' immediate predecessor, international conflicts that led to World War II began to take shape.

[5] It furthered the broad emergency powers already granted to the President, such as the transfer of the seat of government and the extension of the effectivity of lapsing laws.

Upon the reestablishment of the Philippine Commonwealth in Manila in 1945, General Douglas MacArthur exerted political pressure on President Sergio Osmeña to convene Congress in formal session.

Osmeña was reluctant to do so not only because of the huge expense associated with the functioning of Congress, but more so because he feared that its two houses would be controlled by legislators who had collaborated with the Japanese when the Philippine Government was in exile in Washington, D.C. On May 24, 1945, Osmeña offered Roxas the position of Resident Commissioner to the U.S. Roxas by then was known to be actively seeking the right opportunity to launch his presidential ambition with the backing of General Douglas MacArthur, Quezon's former military adviser and considered as the "Liberator of the Philippines."

Two days later, Roxas declined Osmeña's offer and instead asked his supporters to announce his candidacy for president at a time when there was no designated date to hold a national election.

In late May 1945, President Osmeña was persuaded to call the First Commonwealth Congress to special session in order to tackle the most pressing issues of postwar rehabilitation and regain constitutional normalcy.

With the old Legislative Building in ruins, the First Commonwealth Congress met in a former Japanese schoolhouse located at 949 Lepanto Street, Manila, two blocks from the headquarters of Gota de Leche.

Senators Antonio de las Alas, Vicente Madrigal, Quintin Paredes, Claro M. Recto, Proceso E. Sebastian, Emiliano T. Tirona and José Yulo were arrested by the US Army's Counter-Intelligence Corps (CIC) because they had worked in various capacities under the Japanese-sponsored Philippine Government.

The two chambers of Congress assembled in joint session in the afternoon of June 9, 1945, to hear President Osmeña deliver his state of the nation address.

Osmeña expectedly dealt with several proposed legislation to rebuild the financial infrastructure of the Philippines and restore government institutions.

Because of the severe damage caused to property by the war, the legislators who were hurriedly called to Manila in June 1945, including Roxas and Quirino, had no appropriate attire for the congressional sessions other than their army khaki uniforms.

This included U.S. High Commissioner Paul V. McNutt and General MacArthur who received a commendation from the Congress and a second resolution making him an honorary citizen of the Philippines.

51), titled "An Act Governing the Payment of Monetary Obligations Incurred or Contracted Prior to and During the Japanese Invasion of the Philippines and for Other Purposes", was passed by both houses of Congress on the last day of its last session, December 20, 1945.

682 was passed in August 1945 creating the People's Court and the Office of Special Prosecutors to investigate and decide on collaboration charges on an individual basis.

Another currency-related legislation passed by the First Commonwealth Congress was held up for a few weeks at the White House before President Truman signed it into law in November 1945.

5 authorized the Philippine Treasury, which was already financially crippled, to pay back salaries and wages to members of Congress and their staff to cover the three years of Japanese occupation.

This legislation authorized the participation of the Philippine Commonwealth Government in the International Monetary Fund and the World Bank system following the Bretton-Woods Conference in July 1944.

[13] Finally, it was during this historic Congress that the Philippine Senate first exercised its constitutional authority to ratify treaties and other international agreements with its unanimous ratification on August 30, 1945, of the Charter of the newly formed United Nations.

Hence, Osmeña's allies, particularly in the House of Representatives and the Cabinet, exerted every effort to prevent Roxas from using the Congress as his base of political support during the Liberation period.

For example, the Congressional Record of June 11–13, 1945 reports the deliberations in the House of Representatives over Osmeña's Interior Secretary, Tomas Confesor, assertion in the local press that Congress was illegally convened for many reasons, including the expired term of one-third of the senators elected in 1941.

The Osmeña-Roxas rivalry intensified in the Commission on Appointments — a congressional body consisting of 12 senators and 12 congressmen — which was responsible for confirming presidential nominations.

The heat of presidential politics further divided loyalties in the postwar Congress, as its members failed to decide on the date of elections for president, vice-president, 16 senators and 98 congressmen as well as certain electoral provisions (e.g., whether to allow soldiers to vote).