## Facts

- Japan created the Basic Resident Register Network System (Juki-Net), a nationwide network linking municipal resident registers to support administrative functions.
- The system integrated basic identifying data already maintained by municipalities, including residents’ names, dates of birth, sex, addresses, individual residence certificate numbers, and updates to those items.
- Participation was compulsory for residents whose information was included in local resident registers; the system did not provide an individual opt-out.
- Residents sued the national government (and, in some actions, local governments), seeking injunctions and damages, alleging unconstitutional infringement of privacy and control over personal information.
- The statutory scheme restricted access and uses of the data, prohibited unauthorized disclosure and use, imposed penalties, and provided oversight mechanisms.
- Lower courts generally rejected the claims, and the residents appealed to the Supreme Court of Japan (Grand Bench).

## Issues

1. Whether compulsory inclusion of residents’ basic identifying information in a nationwide network violates a constitutionally protected interest in privacy and control over personal information.
2. Whether the network’s purposes, data limits, and safeguards sufficiently reduce the risk of misuse or disclosure such that any interference with privacy is constitutionally permissible.
3. Whether nationwide aggregation and linkage of otherwise routine resident-register data is unconstitutional absent proof of concrete or highly probable harm.

## Decision

- The Supreme Court of Japan (Grand Bench) upheld the constitutionality and legality of Juki-Net.
- The Court rejected the residents’ constitutional privacy challenge and denied injunctive relief and damages.
- The Court treated the system as a limited administrative integration of preexisting resident-register information rather than an expansion into broadly intrusive data collection.
- The Court relied on the statutory purpose limitations, access controls, penalties for misuse, and oversight structure, and found no showing of concrete or highly probable leakage or misuse under the system as implemented.

## Legal Principles

- A constitutional interest in privacy and personal-information control is recognized, but it is not absolute and may yield to legitimate administrative needs when regulation is appropriately bounded.
- Government processing of personal data is more likely to be constitutional where the data categories are limited, the purposes are defined by law, and access and use are constrained.
- Nationwide networking of administrative records is not unconstitutional per se; constitutionality depends on the system’s design, permitted uses, safeguards, and demonstrated risk of serious harm.
- Claims seeking invalidation or damages based on informational privacy require more than abstract fear of aggregation; courts may require a concrete or sufficiently probable risk of misuse or disclosure in the system’s actual operation.

## Conclusion

The Supreme Court of Japan sustained the national resident registry network against privacy-based constitutional challenges, emphasizing the limited nature of the data, the system’s administrative purposes, and statutory safeguards that reduced the risk of serious or imminent privacy harm.


Residents v. Japan, 2007 (Ju) No. 454 (Sup. Ct. Japan Mar. 6, 2008)