Overview

Japanese Law Numbers

Japanese law numbers are a numbering system assigned at the time of promulgation to identify laws, cabinet orders, imperial orders, ministerial ordinances, and rules. Numbers are assigned sequentially from No. 1 for each calendar year according to the type of law and year of enactment, and when the era name changes, numbering starts anew from No. 1 at that point. Assigned based on the promulgation date, they play an important role in uniquely identifying laws, especially when multiple laws share the same title. In the e-Gov law search system, a 15-digit law ID is used to identify laws in a machine-readable format.

law act cabinet order ministerial ordinance e-Gov law number legal system official gazette
code slug name description format lawType lawIdPrefix
1 constitution Constitution The supreme law of Japan. Constitution of Japan (no law number) Constitution
2 act Act Laws established through approval by the National Diet based on constitutional provisions. Era Name Year Act No. X (e.g., Heisei 5 Act No. 88) Act AC
3 cabinet-order Cabinet Order Orders issued by the Cabinet to implement constitutional and legal provisions. Era Name Year Cabinet Order No. X (e.g., Showa 60 Cabinet Order No. 75) CabinetOrder CO
4 imperial-order Imperial Order An old form of law, but includes those still valid at the time data compilation began. Era Name Year Imperial Order No. X (e.g., Showa 18 Imperial Order No. 618) ImperialOrder IO
5 ministerial-ordinance Ministerial Ordinance Orders established by heads of organizations based on laws and cabinet orders. Era Name Year Ministry Ordinance No. X (e.g., Heisei 17 Ministry of Justice Ordinance No. 27) MinisterialOrdinance M1-M6
6 rule Rule Rules such as National Personnel Authority rules, Board of Audit rules, and Supreme Court rules. Era Name Year Rule No. X (e.g., Showa 22 Board of Audit Rule No. 1) Rule R

The numbering system used to identify Japanese laws and regulations.