Q: What are the key powers of the National Diet, including its legislative authority and oversight functions?

The National Diet (国会 - Kokkai), Japan's bicameral parliament, stands at the core of its democratic governance. As stipulated in the Constitution of Japan, it is "the highest organ of state power, and shall be the sole law-making organ of the State" (Article 41). This pronouncement underscores the Diet's preeminent position within the governmental structure. Its authority is not monolithic but encompasses a wide array of crucial functions, ranging from enacting laws and controlling national finances to overseeing the executive branch and participating in international affairs. This article provides a comprehensive overview of these key powers.

1. The Quintessential Power: Legislative Authority (立法権 - Rippōken)

The Diet's primary and most defining power is its legislative authority. Article 41 establishes it as the "sole law-making organ," meaning that only the Diet can enact formal statutes (hōritsu - 法律) that bind the nation.

• The Legislative Process: A bill typically becomes law after being passed by both the House of Representatives (衆議院 - Shūgiin) and the House of Councillors (参議院 - Sangiin). Bills can be introduced by Diet members (often requiring a certain number of co-sponsors), by Diet committees, or, most commonly in practice, by the Cabinet (naikaku teishutsu hōan - 内閣提出法案). After introduction, bills are usually referred to relevant standing or special committees for detailed deliberation and potential amendment before being voted upon in plenary sessions of each House.
• Resolving Inter-House Disagreements: While bicameral agreement is the norm, the Constitution provides mechanisms to resolve disagreements, generally favoring the House of Representatives. If the House of Councillors rejects or fails to act upon a bill passed by the House of Representatives, the bill can still become law if the House of Representatives re-passes it by a majority of two-thirds or more of the members present (Article 59, paragraph 2). For certain critical matters like the budget and treaties, different rules for overriding the upper house apply, further underscoring the lower house's primacy.
• Scope and Limitations: While broad, the Diet's legislative power is not unlimited. It must be exercised in conformity with the Constitution, particularly the provisions guaranteeing fundamental human rights and upholding the rule of law.

2. Control over National Finances (財政を処理する権限 - Zaisei o Shori Suru Kengen)

The Diet wields significant power over the nation's finances, a principle often termed "fiscal democracy" or "parliamentary control of finances," rooted in Article 83 which states that "The power to administer national finances shall be exercised as the Diet shall determine".

• Budgetary Power: The Cabinet is responsible for preparing the annual national budget, but this budget cannot take effect without the Diet's approval (Article 86). The House of Representatives has the prerogative of deliberating on the budget first (Article 60, paragraph 1). The Diet can amend the budget proposed by the Cabinet, reflecting its authority to shape fiscal priorities.
• Taxation: Under the principle of "no taxation without representation" (sozei hōritsu shugi - 租税法律主義), Article 84 mandates that "No new taxes shall be imposed or existing ones modified except by law or under such conditions as law may prescribe". This ensures that the power to levy taxes, a fundamental coercive power of the state, rests with the elected representatives of the people.
• Authorization of Expenditures and Debt: Article 85 requires Diet approval for the state to expend national funds or incur debt. This includes the authorization of government bonds.
• Audit and Accountability: The Diet plays a crucial role in ensuring fiscal accountability. It receives and examines the final accounts of state revenue and expenditure, which are audited annually by the Board of Audit, an independent body (Article 90). Furthermore, the Cabinet must report to the Diet (and the people) on the state of national finances at least once a year (Article 91).

3. Oversight and Scrutiny of the Executive Branch

A vital function of the Diet within Japan's parliamentary cabinet system is to oversee and hold the executive branch (the Cabinet) accountable.

• Designation of the Prime Minister: The Diet designates the Prime Minister from among its own members (Article 67). This act is the foundation upon which the Cabinet is formed and from which it derives its democratic legitimacy.
• Cabinet Responsibility: The cornerstone of the parliamentary system is that the Cabinet is collectively responsible to the Diet (Article 66, paragraph 3). This responsibility is enforced most dramatically by the power of the House of Representatives to pass a non-confidence resolution (or reject a confidence resolution), which compels the Cabinet to either resign en masse or dissolve the House of Representatives within ten days (Article 69).
• Power of Investigation (Kokusei Chōsa-ken - 国政調査権): Article 62 grants each House the power "to conduct investigations in relation to government". This is a broad and potent tool for oversight. It includes the authority to compel the appearance and testimony of witnesses (including government officials) and the production of records. These investigations can cover any aspect of national administration and are intended to equip the Diet with the information necessary for its legislative, budgetary, and oversight functions. While this power is extensive, it is generally understood to be subject to certain limitations, such as respect for judicial independence and fundamental human rights. The PDF also notes the mechanism where the Cabinet can request non-disclosure if testimony would gravely affect vital national interests, though this highlights a point of potential tension.
• Questioning and Demanding Explanations: Article 63 obliges the Prime Minister and other Ministers of State to appear in either House when required to give answers or explanations. This facilitates direct questioning and scrutiny of government policies and actions during plenary sessions and committee meetings.

4. Role in International Affairs

The Diet plays a significant role in shaping Japan's engagement with the international community.

• Treaty Approval (Jōyaku Teiketsu no Shōninken - 条約締結の承認権): While the Cabinet has the power to conclude treaties, Article 73, item 3, requires that such treaties receive the prior or, depending on urgency, subsequent approval of the Diet. This ensures democratic legitimacy for Japan's international commitments. The scope of treaties requiring Diet approval is a matter of established practice, generally including those that involve legislative changes, impose significant financial obligations, or are politically important and require ratification. Administrative agreements of a more technical nature may not require full Diet approval.

5. Power to Initiate Constitutional Amendments

The Diet holds the exclusive power to initiate amendments to the Constitution itself. Article 96, paragraph 1, stipulates that an amendment must be initiated by the Diet, through a concurring vote of two-thirds or more of all the members of each House. The proposed amendment is then submitted to the people for ratification via a national referendum. This power underscores the Diet's role as a guardian of the fundamental law, entrusted with the solemn responsibility of proposing changes to it.

6. Establishment of an Impeachment Court

As a check on the judiciary, Article 64 provides that "The Diet shall set up an impeachment court from among the members of both Houses for the purpose of trying those judges against whom removal proceedings have been instituted". This ensures that judges, while enjoying robust independence and身分保障 (status guarantees), can be removed for serious misconduct or dereliction of duty through a process managed by the elected representatives of the people.

7. Autonomous Powers of Each House (Giin Jishuken - 議院自律権)

In addition to the powers exercised by the Diet as a whole, each House possesses a degree of autonomy over its internal affairs, crucial for its independent functioning. These powers, often referred to as giin jishuken, include:

• Election of its Own Officers: Each House elects its President (or Speaker in the House of Representatives) and other officials from among its members (Article 58, paragraph 1).
• Establishment of Rules: Each House has the power to establish its own rules pertaining to its meetings, proceedings, and internal discipline (Article 58, paragraph 2). This allows each chamber to manage its legislative process and internal order. The relationship between these House rules and the Diet Law (a statute passed by both Houses) can sometimes present complex legal questions regarding internal parliamentary procedure.
• Discipline of Members: Each House has the authority to discipline its members for disorderly conduct during its proceedings. For the gravest offense, a member can be expelled by a vote of two-thirds or more of the members present (Article 58, paragraph 2).
• Judging Qualifications of Members: Each House is responsible for judging disputes relating to the qualifications of its own members (Article 55).
• Immunity and Privileges: While primarily rights of individual members, the Houses play a role in relation to privileges such as immunity from arrest during sessions (Article 50), where a House can demand the release of a member arrested prior to a session or grant or refuse permission for the arrest of a member during a session.

8. Powers Granted by Ordinary Statute

Beyond these constitutionally enumerated powers, the Diet can also be vested with additional functions and authorities through ordinary laws enacted by itself. For example, laws may require Diet approval or consent for certain high-level governmental appointments (such as commissioners of the Board of Audit or the National Personnel Authority) or for specific executive actions, like the dispatch of Self-Defense Forces units for defense operations. This statutory expansion of Diet involvement further reinforces democratic control over various aspects of governance.

Conclusion: The Diet as the Locus of Democratic Legitimacy and Control

The National Diet of Japan is endowed with a broad and diverse range of powers that position it as the central institution in the nation's democratic framework. Its legislative supremacy, control over national finances, extensive oversight capabilities regarding the executive, and role in constitutional amendment and international affairs collectively underscore its constitutional designation as the "highest organ of state power." While the practical dynamics of these powers are often shaped by the parliamentary cabinet system and the prevailing political landscape, the Diet's constitutional mandate remains fundamental to ensuring accountable, representative, and law-based governance in Japan.