I gave a presentation at the LAEASIA Workshop on Data Protection in Tokyo on August 29-30, 2025:Data Protection Laws on the Move in the Asia-Pacific Region | LAWASIA.

The　presentation was on three important case precedents regarding personal information protection in Japan. The details are as follows:

I’d like to share two Supreme Court of Japan case precedents concerning the Act on the Protection of Personal Information (APPI).

And I will also introduce one more Supreme Court case related to privacy.

Therefore, I will be introducing a total of three Supreme Court cases today.

1. Case on a Prisoner’s Medical Records

The first case involves a disclosure request for a prisoner’s medical records under the APPI.

It’s important to note that the Japanese APPI was amended in 2021. Prior to this, there were many separate laws: one for administrative agencies and one for the private sector. The 2021 amendment combined these many laws into a single act. The case I will be discussing is a precedent from before the 2021 amendment, concerning the law for administrative agencies, but its contents still apply to the current APPI.

Japan’s APPI allows individuals to request the disclosure of their personal information from administrative agencies. However, information related to the execution of a sentence is typically excluded from disclosure. Because of this, administrative authorities have long refused to disclose a prisoner’s medical records, even when a request was made under the APPI.

However, a Supreme Court decision on June 15, 2021, ruled that a prisoner’s medical records are subject to disclosure under the APPI. The Supreme Court made this decision based on the legislative process of the law. Additionally, Justice Uga’s supplementary opinion cited international rules, such as the Nelson Mandela Rules, as a basis for the ruling.

Since Japanese case law rarely references international human rights law, this supplementary opinion—which cites international rules—is considered a significant precedent for its influence on judicial decisions.

2. Case on Information of Deceased Individuals

The second case is a Supreme Court decision from March 18, 2019, regarding disclosure requests for information about deceased individuals.

Similar to data protection laws in other countries, Japan’s APPI primarily applies to the personal information of living individuals. Therefore, information about a deceased person is not generally subject to a disclosure request under the APPI.

However, there are cases where a deceased person’s information can also be considered the personal information of a living individual. In such cases, the information can be subject to a disclosure request. The Supreme Court’s March 18, 2019, decision determined when a disclosure request for a deceased person’s information can be made under the APPI.

The Supreme Court ruled that whether information regarding a deceased person’s estate constitutes personal information of a living requester must be determined on a case-by-case basis, by individually examining the content of the information and its relationship to the person making the request.

Based on this Supreme Court decision, several lower court rulings have emerged. These rulings have established a trend of allowing disclosure requests for information about a deceased person’s estate—such as details necessary for a living heir to exercise their rights to a claim for damages—as the personal information of the requester.

However, it remains somewhat ambiguous as to what extent deceased person information can be disclosed.

３．Supreme Court Ruling on GPS Tracking of Vehicles

The third point is the Supreme Court ruling of March 15, 2017, concerning the investigative method of attaching a GPS device to a vehicle.

Article 35 of the Constitution of Japan guarantees the right of people to be free from entry, search, and seizure of their homes, papers, and belongings without a warrant.

Historically, the focus of this article was on acts such as the seizure of objects. Therefore, it was not clear whether a warrant was constitutionally required for an investigation that involved attaching a GPS device to a vehicle and obtaining a record of its movements.

In its March 15, 2017 ruling, the Supreme Court stated that the protection of Article 35 is not limited to “homes, papers, and effects,” but also includes the right to be free from “intrusion” into a private domain equivalent to these.

Furthermore, regarding the investigative method of attaching a GPS device to a vehicle, the court determined that it “inevitably involves the continuous and comprehensive tracking of an individual’s behavior, and therefore can infringe on an individual’s privacy.” It further stated that this method “should be considered an intrusion by public authority into a private domain.”

As a result, the court explicitly stated that a warrant is required for investigative methods that involve attaching a GPS device to a vehicle.

Following this Supreme Court precedent, the National Police Agency instructed police forces nationwide to refrain from using this method of investigation.

The court’s decision that a warrant is required for investigative methods that continuously track an individual’s actions and infringe on their privacy is believed to apply to other forms of investigation beyond GPS tracking, and it has a significant impact on how investigations are conducted.

Tel（０２５－２１１－４８５４）、E-mailメール

Topさいとうゆたか法律事務所トップ