Legal study and government service
Inoue came from a Kumamoto samurai family and joined the Ministry of Justice in 1871. European study followed in 1872–73. His work included French and German legal institutions and participation in publishing a Japanese translation concerned with the Prussian constitution.
He accompanied Ōkubo Toshimichi to Qing China in 1874. Working subsequently for Iwakura and Itō Hirobumi, he drafted policy proposals, including plans for an imperially granted constitution and the 1881 announcement of a future parliament.
Successive constitutional drafts
Constitutional drafting involved several officials rather than a single author. Preliminary work by Inoue and the German adviser Hermann Roesler was revised with Itō, Itō Miyoji and Kaneko Kentarō. Discussions at Itō's Natsushima villa in 1887 produced a draft that underwent further revision and Privy Council deliberation.
As the council's chief secretary from 1888, Inoue helped manage its constitutional proceedings. Surviving alternative drafts use different arrangements of preamble and articles, with handwritten corrections recording choices made before the constitution's promulgation in February 1889.
Education and the Goin papers
Inoue helped draft the 1890 Imperial Rescript on Education and became education minister in the second Itō cabinet in 1893. His other drafting work concerned the imperial household and higher schools, extending beyond the constitution itself.
His papers and books survive in Kokugakuin University's Goin Collection, named for his literary name. Student notebooks, constitutional drafts, treaty-revision opinions and parliamentary materials preserve the working record of a legal official. He was distinct from the similarly named politician Inoue Kaoru.