Supreme Court, Second Petty Bench · January 30, 2023 · Reiwa 3 (2021) (Ju) No. 2050 · Judgment: quashed with the Court's own decision

A person whose rights were infringed by a post made before the 2020 ministerial ordinance added telephone numbers to the categories of sender information may, after that ordinance took effect, demand disclosure of the sender's telephone number.

Case seeking disclosure of sender identification information

Facts

In November 2018, an anonymous post on an internet bulletin board gave the impression that the plaintiff, a company officer, was lining his own pockets, and ridiculed his appearance. In June 2019 the plaintiff sued the access provider that had served the poster, seeking the poster's name, address and other information. The Ministry of Internal Affairs and Communications ordinance defining sender information was amended, with effect from August 31, 2020, to add the sender's telephone number. In September 2020 the plaintiff added a claim for the telephone number in the court below. That court dismissed the added claim, holding that allowing disclosure of a telephone number for an infringement that predated the amendment would infringe the sender's secrecy of communications and freedom of expression, and that nothing authorized retroactive application.

Issue

Whether, for a post made before the ordinance added telephone numbers to sender information, disclosure of the telephone number may be demanded after the amendment under Article 4(1) of the Act (before the 2021 amendment).

Ruling

Article 4(1) of the Act was not amended between the Act's entry into force and the 2021 amendment. The amending ordinance contains no transitional provision excluding the amended ordinance from disclosure claims concerning infringements that predate it, so claims made after the amendment are governed by the amended ordinance regardless of when the infringing information was distributed. Article 4(1) delegated the definition of disclosable information to a ministerial ordinance so that the categories could be adjusted promptly as technology and social conditions change, and the amendment merely added telephone numbers. It cannot be read as confining telephone numbers to infringements occurring after the amendment. A person whose rights were infringed before the amendment may therefore demand disclosure of the sender's telephone number afterwards. The Court quashed the part of the judgment below concerning the added claim and ordered disclosure of the telephone number. Unanimous.

Provisions

Provider Liability Limitation Act (before the 2021 amendment), Art. 4(1); Ministerial Ordinance Specifying Sender Information under Art. 4(1), item 3