Q: What was the process behind the enactment of Japan's current Constitution, and what are the legal theories explaining its establishment?

Japanese Attorney at Law - Bengoshi L.L.

• 7 min read

The Constitution of Japan, promulgated on November 3, 1946, and enacted on May 3, 1947, stands as a monumental document that fundamentally reshaped the nation's political and legal landscape in the aftermath of World War II. Its creation was a complex and unique process, heavily influenced by the Allied Occupation, yet also involving significant Japanese contributions. Understanding this enactment process, alongside the various legal theories developed to explain its legitimacy and nature, is essential for a comprehensive grasp of modern Japanese constitutionalism.

The Catalyst: Defeat and the Potsdam Declaration

The journey towards Japan's current Constitution began with its surrender in August 1945 and the acceptance of the Potsdam Declaration. Issued on July 26, 1945, by the United States, Great Britain, and China (later joined by the Soviet Union), this declaration outlined the terms for Japan's unconditional surrender. Crucially, it called for the "elimination of the authority and influence of those who have deceived and misled the people of Japan into embarking on world conquest," the establishment of "freedom of speech, of religion, and of thought, as well as respect for the fundamental human rights," and the creation of "a peacefully inclined and responsible government... in accordance with the freely expressed will of the Japanese people" (Potsdam Declaration, Articles 6, 10, 12).

The Japanese government, after intense internal debate, particularly concerning the preservation of the imperial institution (kokutai goji), accepted the Declaration on August 14, 1945. This acceptance set the stage for sweeping reforms under the Allied Occupation, led by the Supreme Commander for the Allied Powers (SCAP), General Douglas MacArthur.

Early Japanese Efforts at Constitutional Reform

Following the surrender, the Japanese government initiated its own efforts to revise the Meiji Constitution of 1889. In October 1945, Prime Minister Kijūrō Shidehara (幣原喜重郎) established the Constitutional Problem Investigation Committee (憲法問題調査委員会 - Kenpō Mondai Chōsa Iinkai), commonly known as the Matsumoto Committee, chaired by Minister of State Jōji Matsumoto (松本烝治).

The Matsumoto Committee's work, however, proved to be conservative. Their draft proposals, often referred to as the "Matsumoto Draft" (松本案 - Matsumoto-an), aimed for relatively minor revisions to the Meiji Constitution, fundamentally seeking to preserve the Emperor's sovereign status and the existing state structure, albeit with some expansion of parliamentary powers and individual rights. This approach was perceived by SCAP as falling far short of the democratic reforms envisioned by the Potsdam Declaration. A significant event during this period was Emperor Hirohito's "Humanity Declaration" (Ningen-sengen) on January 1, 1946, in which he publicly disavowed his own divinity, a move that had profound implications for the redefinition of the Emperor's role.

The GHQ/SCAP Intervention: A New Constitutional Blueprint

Dissatisfied with the pace and substance of the Japanese government's efforts, SCAP's Government Section took the initiative to draft its own constitutional model. This was partly spurred by concerns that a conservative Japanese proposal would be unacceptable to the Far Eastern Commission (FEC), an international body established to oversee Allied policy in Japan, where some member states held strong views favoring the abolition of the Emperor system.

On February 3, 1946, General MacArthur issued three guiding principles for the new constitution to his staff, commonly known as the "MacArthur Notes" or "MacArthur's Three Principles" (マッカーサー三原則 - Makkāsā San Gensoku). These were:

  1. The Emperor is at the head of the state. His succession is dynastic. His duties and powers will be exercised in accordance with the Constitution and responsive to the basic will of the people as provided therein.
  2. War as a sovereign right of the nation is abolished. Japan renounces it as an instrumentality for settling its disputes and even for preserving its own security. It relies upon the higher ideals which are now stirring the world for its defense and its protection. No Japanese Army, Navy, or Air Force will ever be authorized and no rights of belligerency will ever be conferred upon any Japanese force.
  3. The feudal system of Japan will cease. No rights of peerage except those of the Imperial family will extend beyond the limits of existing law. The budget in the form of an annual statement of income and expenditures will be patterned after the British system.

Working intensively for about a week, the SCAP staff produced a comprehensive draft. On February 13, 1946, this draft, often called the "GHQ Draft" or "MacArthur Draft," was presented to the astonished Japanese government. It was a radical departure from the Meiji Constitution, embodying principles such as popular sovereignty, the symbolic status of the Emperor, an extensive bill of rights, the renunciation of war, and a parliamentary cabinet system. Faced with SCAP's insistence and the implicit understanding that acceptance was crucial for the preservation of the Emperor system itself, the Japanese government had little choice but to use this draft as the basis for its own proposal. There is evidence that SCAP also drew upon various sources, including the SWNCC-228 document (a U.S. State-War-Navy Coordinating Committee paper on Japanese governmental reform) and proposals from Japanese civilian groups like the Constitution Investigation Association (憲法研究会 - Kenpō Kenkyūkai).

Japanese Adaptation and Deliberations in the Imperial Diet

The Japanese government, led by Prime Minister Shigeru Yoshida (吉田茂) who succeeded Shidehara, worked to translate and adapt the GHQ draft into a Japanese proposal. This culminated in the "Outline of the Draft Constitution" (憲法改正草案要綱 - Kenpō Kaisei Sōan Yōkō), made public on March 6, 1946 (often referred to as the "March 6th Draft"). While based on the GHQ draft, it included some modifications, most notably the change from a unicameral to a bicameral legislature.

This draft was then transformed into a formal bill for constitutional revision, presented in colloquial Japanese, and submitted to the Privy Council (枢密院 - Sūmitsuin) for deliberation, and subsequently to the 90th session of the Imperial Diet in June 1946. This Diet had been elected in April 1946 under a revised election law that, for the first time, granted suffrage to women.

The deliberations in the Imperial Diet, particularly in the House of Representatives' Special Committee on Constitutional Revision, were extensive and involved numerous amendments. Notable among these was the "Ashida Amendment" (芦田修正 - Ashida Shūsei), named after committee chairman Hitoshi Ashida (芦田均), which modified the wording of what became Article 9, the war renunciation clause. Another significant addition, made at the request of the Far Eastern Commission, was the provision requiring Ministers of State to be civilians (now Article 66, paragraph 2). Minister of State Tokujirō Kanamori (金森徳次郎) played a central role in defending the government's draft and explaining its principles during these Diet debates, famously arguing that the kokutai (national polity) had not been altered in its essence, with the Emperor remaining the focal point of national unity, albeit in a new symbolic role.

After passing both Houses of the Imperial Diet (with amendments), the revised Constitution was promulgated on November 3, 1946, and came into effect on May 3, 1947.

The unique circumstances of its enactment have given rise to several legal theories attempting to explain the legitimacy and nature of the Constitution of Japan.

  1. The Principle of Constitutional Autonomy (憲法の自律性 - Kenpō no Jiritsusei):
    A key debate revolves around whether the Constitution, given the strong SCAP influence, can be considered an autonomous creation of the Japanese people. The prevailing scholarly view in Japan argues that its autonomy was not fatally compromised. The reasoning includes: (a) Japan's acceptance of the Potsdam Declaration, which itself mandated democratic reforms and human rights protections, created an international legal obligation; (b) public opinion at the time, to the extent it can be gauged, was largely supportive of the core democratic principles of the SCAP draft; (c) the Japanese government, at least by the Diet deliberation stage, had endorsed the fundamental content; and (d) the Constitution was deliberated and approved by a Diet whose House of Representatives was elected under universal suffrage. Some also argue that in a modern international society where principles like popular sovereignty and human rights are widely shared, requiring their adoption during constitution-making does not necessarily violate constitutional autonomy. Arguments that the process violated the Hague Convention of 1907 (respecting laws in force in occupied territory) are generally dismissed, as the Convention is seen to apply to belligerent occupation, whereas Japan's situation was a post-surrender occupation governed by the terms of the Potsdam Declaration.
  2. The August Revolution Theory (八月革命説 - Hachigatsu Kakumei-setsu):
    This influential theory, prominently advocated by jurist Toshiyoshi Miyazawa (宮沢俊義), addresses the apparent legal contradiction between the Meiji Constitution (based on imperial sovereignty) and the new Constitution (based on popular sovereignty), despite the latter being formally enacted through the amendment procedures of the former (Article 73 of the Meiji Constitution). The theory posits that Japan's acceptance of the Potsdam Declaration in August 1945 constituted a legal "revolution". At that moment, the fundamental principle of imperial sovereignty was superseded by popular sovereignty. Consequently, the Meiji Constitution, including its amendment clause, underwent a profound transformation in substance, if not in form. The new Constitution was, in reality, a "new enactment" (shinkenpō no seitei) based on popular sovereignty, and the use of the Meiji Constitution's amendment procedure was merely a "convenient fiction" or a practical measure to ensure a smooth transition and maintain legal continuity in appearance. This theory helps reconcile the change in sovereignty with the theory of limitations on constitutional amendment (which generally holds that a change in the sovereign power itself is beyond the scope of mere amendment).
  3. Critiques of the August Revolution Theory:
    While widely supported, the August Revolution Theory has also faced criticism. Critics question whether the Potsdam Declaration explicitly mandated a shift to popular sovereignty with immediate domestic legal effect, or whether it merely imposed international obligations that required subsequent domestic legal implementation. Some argue that to see an immediate transformation of sovereignty solely based on the Declaration's acceptance necessitates a radical monist view of international law's relationship with domestic law. Alternative explanations suggest that the acceptance of the Potsdam Declaration created international duties for Japan, and Emperor Shōwa, in fulfilling these duties, initiated the constitutional revision process. During the Diet deliberations, the will of the people, acting as the constituent power, became manifest, and the Meiji amendment procedure was "borrowed" for political expediency. However, this view struggles to explain state practices between the surrender and the new Constitution's enforcement that already seemed to reflect a shift, such as the Emperor's Humanity Declaration.

Conclusion: A Constitution Forged in Transition

The enactment of the Constitution of Japan was a complex tapestry woven from threads of defeat, occupation, international pressure, and domestic political maneuvering. It marked a decisive break from the imperial system of the Meiji era and laid the foundation for a democratic and pacifist nation. While the heavy involvement of SCAP, particularly in the drafting stage, has led to persistent debates about its "imposed" nature, the process also involved significant Japanese agency in adaptation, deliberation, and formal adoption through its existing (though soon-to-be-abolished) constitutional mechanisms. The legal theories surrounding its establishment, such as the August Revolution Theory, continue to provide a framework for understanding the Constitution's legitimacy and its relationship with Japan's pre-war legal order. Ultimately, the Constitution's endurance and its role in shaping post-war Japanese society attest to its acceptance and its function as the nation's fundamental law.