The Imperial House Law: From the Drafting Struggles of the Meiji Era to Modern Succession Issues

April 28, 2025

The current Imperial House Law was enacted in 1947 alongside the Constitution of Japan. Nearly 80 years have passed since then, and while various institutional contradictions have been pointed out during that time, legal reform has yet to be achieved.

The fact that the post-war Imperial House Law limited succession eligibility to legitimate offspring and maintained the "male-line male" principle, following the pre-war law, has destabilized the imperial succession. As the birthrate declined in the 1990s, the Imperial Family was no exception, and the decrease in the number of imperial family members became prominent.

Consequently, in the late 1990s, the Cabinet Secretariat, the Imperial Household Agency, and the Cabinet Legislation Bureau held secret study groups at the Akasaka Prince Hotel, where a draft for amending the Imperial House Law for stable succession was quietly prepared. This draft culminated in the November 2005 report by Prime Minister Koizumi's private advisory body, the "Advisory Council on the Imperial House Law."

Since then, there have been various debates regarding the imperial succession, but there is no doubt that this report remains an important starting point. The report was immediately drafted into a bill and scheduled for submission to the ordinary Diet session. However, just then, news of Princess Kiko of Akishino's pregnancy broke, and the discussion was temporarily shelved.

With the birth of Prince Hisahito in September of that year, the public debate subsided as if the problem had been solved. However, can we truly say that the imperial succession has stabilized just because one male was born into the generation following the current Emperor Naruhito and Prince Akishino?

Except for Prince Hisahito, the relatively young members of the Imperial Family are all female. It is expected that female members will eventually leave the Imperial Family upon marriage. Can we truly ensure there will be enough imperial family members to support Prince Hisahito in the future? This book re-examines the contradictory Imperial House Law, from the struggles surrounding its Meiji-era drafting to the process of establishing the current law as a subordinate law to the post-war Constitution, clarifying the political background of the still-unresolved succession issue.

Following the Koizumi Cabinet, the Noda, Abe, and Suga Cabinets approached this issue, but a solution remains elusive. For a resolution, research into procedures is as important as institutional design. From the beginning, conservatives within the LDP who strictly adhere to the "male-line male" principle have hindered a solution to this problem.

In this book, a "greatest common divisor"—one that does not shy away from wise compromise—is pursued.

The Imperial House Law: From the Drafting Struggles of the Meiji Era to Modern Succession Issues
Hidehiko Kasahara

Chuko Shinsho

256 pages, 990 yen (tax included)