Most Japanese textbooks describe Article 9, paragraph 1 of the Constitution as a renunciation of wars of aggression. Constitutional scholar Yasuo Hasebe says he cannot find where that reading comes from.
The clause renounces war as a means of settling international disputes, and Hasebe argues it should be read in those words: not only aggression is banned, but any use of force or threat of force in a dispute between states, including a border clash. The basis for that reading, he says, is the 1928 Kellogg-Briand Pact, which Japan signed.
He makes the case in a dialogue with political scientist Atsushi Sugita, published as the Asahi Shinsho book Positive Pacifism, timed to the 80th anniversary of the promulgation of the Constitution. The passages below are drawn from that book.
A pact against war as a duel
Article 1 of the Kellogg-Briand Pact, also known as the Pact of Paris, forbids recourse to war for the settlement of international disputes in wording almost identical to Article 9, paragraph 1. Behind the treaty lay a rethink of a view of international law that dated to the Dutch jurist Grotius (1583-1645).
War was understood as a duel between states: the winner was in the right, and the loser had to submit. By that standard, Commodore Perry's entry into Edo Bay to force open the country was not illegal, Hasebe says. After the carnage of World War I, the powers signed the pact to give up the duel, and Japan was among them.
The pact bans dueling only, so it does not forbid a state from exercising individual self-defense when attacked, Hasebe argues. The international law scholar Ryutaro Tachi (1874-1943), then at Tokyo Imperial University, argued the same, and US Secretary of State Frank Kellogg (1856-1937) told the Senate during ratification that the treaty did not deny the right of self-defense.
Read with that logic in mind, paragraph 1 says Japan will not fight wars as duels. The phrase "in order to accomplish the aim of the preceding paragraph" in paragraph 2 then means "in order not to duel", which is why Japan will not maintain war potential or recognize the right of belligerency. The two paragraphs hold together as one coherent provision, he says.
The dominant view has been the reverse: that paragraph 1 renounces only wars of aggression while paragraph 2 denies all war potential, including for self-defense, leaving the two paragraphs saying separate things. Hasebe calls that reading incoherent. If a coherent reading exists, he says, it should be adopted, and this one also carries forward the logic of the pact.
“I really wonder why everyone has kept repeating such an obvious mistake.”Yasuo Hasebe, constitutional scholar
"Most constitutional scholars are not interested"
Sugita asks whether constitutional scholars simply never read what international lawyers had written about the pact. Hasebe points to an article by the international law scholar Yuichi Takano that set out the relationship accurately, published in 1965 in a collection on the Japanese constitutional system (Yuhikaku).
Constitutional scholars probably did not read it, Hasebe says, and many seem to have little interest in Article 9 at all. Thinking stops at "everyone says so, so it must be true", he says, when study would show the problem.
Sugita pushes back: saying they are uninterested is an evasion, when revisionists are attacking exactly this ground. Hasebe replies that most constitutional scholars do not feel they are under attack, because they were never interested in Article 9 to begin with.
Constraint as strength
Sugita notes the limits of the pact: Japan, one of its signatories, called its invasion of Manchuria the "Manchurian Incident" and argued it was not war and so not a treaty violation. The pact did not prevent World War II, and the UN Charter of 1945 has hardly worked smoothly, he says, with violations of international law widespread.
Hasebe argues that most US presidents have largely kept to international law because it serves the country's interest over the long run. A reputation for tearing up treaties when they become inconvenient means no one will sign a serious one with you, and no one will believe a promise that force will not be used if concessions are made. He cites that as one reason a US-Iran conflict that began in 2026 has been hard to resolve.
On Japan's own Constitution, he says no provision other than Article 9 suggests that the use of force is permitted. The baseline is zero: force is in principle prohibited, and allowed only where strictly necessary. That is why successive governments have held that individual self-defense is permitted as the minimum force needed to protect the people's rights to life, liberty and the pursuit of happiness, while collective self-defense is not.
Suppose Article 9 were abolished entirely and Japan's authority expanded to allow full collective self-defense. Would its actual capability rise? Japan's neighbors include the US, China and Russia, and matching them militarily is not realistic, he says. Limiting authority to what the country's strength can support lets it refuse demands it cannot meet.
If asked to send the Self-Defense Forces to the Strait of Hormuz, Japan can say no because Article 9 exists, he says, and put that energy into diplomacy instead. Restricting authority, in his account, raises real capability.