A snippet from Guha (about Japan)

A piece of information that I did not know about Japan:

… a new constitution had been presented for approval to the Japanese parliament, the Diet. This document had been almost wholly written by a group of foreigners. In early February 1946, twenty-four individuals –all Americans, and sixteen of them military officials–met in a converted ballroom in Tokyo. Here they sat for a week, before coming up with a constitution they thought the Japanese should adopt. This was then presented as a fait accompli to the local political leaders, who were allowed to “Japanize” the draft by translating it into the local tongue. The draft  was also discussed in the Diet, but every amendment, even the most cosmetic, had to be approved by the American authorities.

Wiki gives a slightly better perspective on the reasons as to why the Japanese might have allowed such a drafting:

Prime Minister Shidehara Kijuro and many of his colleagues were extremely reluctant to take the drastic step of replacing the 1889 Meiji Constitution with a more liberal document.

In fact, Wiki goes on to inform us,

in adopting the new document the Meiji Constitution would not be violated, but rather legal continuity would be maintained. Thus the 1946 constitution was adopted as an amendment to the Meiji Constitution in accordance with the provisions of Article 73 of that document.

Interesting!