Koyata Iwahashi

...The first time this was seen in the enthronement decree of Emperor Genmei in 707 (Keiun 4) in the Shoku Nihongi, it read, "Emperor O-Wa-neko, who reigned in the majestic Otsu Palace in Omi, is as long as the heavens and the earth, as far as the sun and the moon, and is an unalterable and eternal law." The modification was simplified thereafter, but it appears in the enthronement decrees of both Emperors Shomu and Koken. In the past, this was interpreted as referring to the Taika Reform Edict or the Omi Code enacted by Emperor Tenchi, but in 1951, Iwahashi Koyata denied the old theory, arguing that the Taika Reform Edict and the Taiho Code, which was developed from the Omi Code, contained no provisions regarding imperial succession, and that the Omi Code had been altered after its enactment and could not be said to be "unaltered," and that it was a system of direct succession to the throne that was established separately from them. After that, many arguments arose about Iwahashi's theory. ...

*Some of the terminology explanations that refer to "Iwahashi Koyata" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…《続日本紀》にみえる707年(慶雲4)の元明天皇即位の宣命に，〈関（かけまく）も威（かしこ）き近江の大津宮に御宇（あめのしたしろしめ）しし大倭根子天皇の，天地と共に長く日月と共に遠く，改るまじき常の典〉とみえるのが初見で，以後修飾は簡略になるが，聖武･孝謙の両天皇の即位宣命にみられる。これは古くは大化改新の詔，または天智天皇の制定した近江令を指すと解せられていたが，1951年に岩橋小弥太が，大化改新詔や，近江令を発展させた大宝令には皇位継承に関する規定のないこと，近江令は制定後改変され〈不改〉といえないことなどから，旧説を否定し，それらとは別に定めた皇位直系相続の制であるとした。その後，岩橋説をめぐり多くの論が出た。…

※「岩橋小弥太」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報