It may surprise some readers (but perhaps not others) that Japan has no official language. This may seem trivial, but remember that Japan’s constitution, the basis of its entire legal system, was largely drafted by US lawyers and then translated into Japanese (which is why the Japanese language, such as randomly granting rights to “citizens” or “anyone” without a meaningful discrepancy, is so scattershot). What, then, is the law regarding the use of Japanese, and where is Japanese language use mandated by law?
The instances are surprisingly few. Perhaps the most important is Article 74 of the Courts Law:
Article 74: In the courts, the Japanese language shall be used.
The pre-war Foreign Courts Cooperation Law also provides that any document submitted to the Japanese courts must contain a Japanese translation.
The other instances are pretty minor and frankly merely procedural:
* Japan’s Patent Law and other related intellectual property laws requires that all international patent registration documents be submitted in Japanese. These laws were primarily amended to bring Japanese domestic law into line with the international treaties on IP registration that Japan has signed.
* Under the Notary Public Law, notaries can draft proof documents — that are in Japanese.
* Foreign doctors doing clinical work in Japan must speak Japanese, or another language approved by the Ministry of Health Labour and Welfare.
* The conversion of a foreign driver license requires that it be translated into Japanese by an officially approved translation body, under Article 107-2 of the Road and Transport Law.
* Foreign company reports designated by the cabinet to contain public interest information or information for the protection of investors must be in Japanese, under Article 24 of the J-SOX Law.
In my search of the Japanese law database houko.com, those are the only significant instances where the law mentions Japanese.