Lawfare:
The Japanese Constitution was long understood as prohibiting the exercise of international law’s right of collective self-defense under all circumstances. Until just a few years ago, the government’s view had been that the Constitution’s war-renouncing clause, Article 9, permitted only the use of minimum necessary force to defend the territory and population of Japan—not other countries.
So for Japan to use force in collective self-defense (or even in instances authorized by the U.N. Security Council under Chapter VII of the U.N. Charter) would have been considered unconstitutional by the government because it would have exceeded this threshold. Japan could legally defend the population of a foreign state only if that population was in Japanese territory, such as American troops stationed in Japan (an issue I discussed on Lawfare as a matter of Japan’s individual self-defense with the United States).
This long-standing legal situation changed dramatically in 2014. Amid a lingering split in public opinion, Japan’s Cabinet decided to lift the ban on collective self-defense, particularly in a bid to “strengthen mutual cooperation with the United States.” This was not done by revising the Constitution—which has not been amended in its 72-year history—but, instead, by reinterpreting its principle of minimum necessary force, which continues to limit the scope of Japan’s permissible actions toward collective self-defense.
