SAKURA Law Office is pleased to announce that our attorney Naoki Kanayama (Professor Emeritus of Keio University and Director of the SAKURA Institute of Legal Studies) will present research on “Whether Compensation for Emotional Distress May Be Claimed Against the Other Party to an Extramarital Affair” at the Civil Law Case Study Group (Minji-ho Hanrei Kenkyukai), to be held on Saturday, November 14, 2026, in the conference room of the Japan Bar Association (Nihon Horitsuka Kyokai).
The subject of the presentation is a judgment of the Second Petty Bench of the Supreme Court delivered on June 5, 2026, in a damages case (Reiwa 7 (2025) (Ju) No. 933). In a claim for compensation for emotional distress (solatium) against a third party alleged to have engaged in an extramarital affair with one spouse, the Court held that the High Court’s finding of negligence on the part of the third party was unlawful in that it erred in interpreting and applying the law on negligence, reversed the judgment below in part, and remanded the case to the Takamatsu High Court for further proceedings.
Claims for compensation for emotional distress arising from extramarital affairs are a matter between spouses, but at the same time they raise an important civil law question: in what circumstances may tort liability be recognized against a third party alleged to have been the other party to the affair? While it is necessary to protect the rights and interests concerning the maintenance of peace in married life, one must also be cautious about uniformly affirming the liability of a person alleged to be the other party without sufficiently examining the actual state of the marriage and the person’s own awareness.
What the Supreme Court addressed in this case is that two questions must be examined separately: whether the third party had reasonable grounds to believe that the spouses “had already divorced,” and whether the third party believed that the marriage “had already broken down” and had reasonable grounds for that belief. The court below found negligence on the basis of the former; however, the Supreme Court held that, since the court below had not carried out the necessary examination of the latter, negligence on the part of the third party could not be found immediately. Accordingly, the judgment neither denied the liability of third parties in all cases of extramarital affairs nor finally determined that a particular third party bears no liability.
The issue raised by this judgment leads to a more fundamental question: as what kind of infringement of rights and interests should the liability of a third party involved in an extramarital affair be understood, and on the basis of what circumstances should intent or negligence be determined? Examining closely the actual state of the marital relationship, the parties’ awareness and the circumstances that give rise to liability, while bearing in mind continuity with the existing case law, will be an important task of this presentation.
Connection to Mr. Kanayama’s Research
For many years, Mr. Kanayama has been engaged in research and education centered on civil law and comparative law, and since registering as an attorney in 2018 he has also handled damages cases involving sexual harm. In particular, in “Sexual Acts and Consent: Freedom and Coercion Under Structural Inequality” (Hogaku Kenkyu, Vol. 92, No. 9, 2019) and “Sexual Acts and Damages: Toward a Reconstruction of Solatium, Parts 1 & 2” (Vol. 93, Nos. 2 and 3, 2020), he examines, from the perspective of civil law, free decision-making and responsibility in sexual relationships.
Behind Mr. Kanayama’s strong interest in this issue is his awareness, formed through his research and case work to date, that disparities in position in the workplace and elsewhere, as well as psychological pressure, may give rise to sexual acts that cannot be called the product of a person’s free will. In practice, there are cases in which a victim who claims to have been forced into sexual acts against their will, and who seeks compensation for emotional distress for the harmful conduct, is concerned that, because the other party was married, the other party’s spouse may in turn claim compensation from the victim.
In such cases, it is not appropriate to discuss a third party’s tort liability immediately on the sole ground that, on the surface, a sexual relationship with a married person existed. It is necessary to examine carefully, on the facts, the circumstances and power relations under which the sexual relationship arose, whether genuine consent existed, and whether there is any basis for attributing responsibility to the person regarded as the victim of the harmful conduct. However, the Supreme Court judgment to be discussed is itself not a case that determined the existence of sexual coercion. This presentation takes that judgment as a starting point to re-examine, from a broader perspective, the basis for compensation for emotional distress in extramarital affairs and the limits of liability.
Where the interests arising from the marital relationship are infringed by an extramarital affair, how should responsibility be considered, first, as against the spouse who engaged in the affair, and what is the basis for recognizing tort liability even against the person alleged to be the other party? These questions concern the principles of civil liability themselves, beyond the outcomes of individual cases. Through this presentation, Mr. Kanayama plans to examine the existing case law carefully and to deepen the theoretical analysis of whether compensation for emotional distress may be claimed against the other party to an extramarital affair.
The Study Group and Future Initiatives
The study group will be held from 1:30 p.m. on Saturday, November 14, 2026, in the conference room of the Japan Bar Association, 1-1-1 Kasumigaseki, Chiyoda-ku, Tokyo, and, according to the organizer’s notice, attendance via Zoom is also possible. This announcement is based on the notice of the meeting sent to the study group’s members, and it does not mean that applications to participate from the general public are being accepted.
Mr. Kanayama plans to publish the results of this research presentation in legal journals such as The Rule of Law (Ho no Shihai) or Kinyu Shoji Hanrei (Financial and Commercial Case Law Reports). We will announce the journal and the timing of publication once they are formally decided.
SAKURA Law Office places importance on connecting the results of civil law research to the resolution of actual disputes. While supporting Mr. Kanayama’s academic activities, we will handle legal consultations and cases, with full consideration of individual circumstances, regarding claims for compensation for emotional distress arising from extramarital affairs, responses to damages claims against third parties, disputes concerning marital relationships, and civil cases in which the existence of sexual consent is at issue.
If you have received a claim for compensation for emotional distress on the ground of an extramarital affair, are considering a claim against a spouse or the other party, or wish to consult about harm involving sexual relationships and damages, please contact us through our contact form. In consultations, we will review the relationship between the parties, the course of events, relevant materials and case law, and consider individually whether and how we can respond and what the appropriate legal approach is.
Contact
SAKURA Law Office Official Contact Form
https://sakura-lawyers.jp/en/contact/
4F, Ark Hills South Tower, 1-4-5 Roppongi, Minato-ku, Tokyo 106-0032, Japan
Managing Partner Kenshiro Michishita