Human beings are complicated. This is probably because human beings are creatures falling in love. I believe that there is no difference on this point wherever you are in the world.

However, I can say that there are some differences between countries, at least from a legal perspective. Unlike some common law countries such as the U.S., Singapore, and Hong Kong, Japanese courts recognize claims for damages arising from mental distress based on tort if a third party has a love affair with a married person.  The amount of damages varies from case to case, but a rough guide from previous court decisions ranges from 500,000 JPY to 3,000,000 JPY.

In this article, l would like to talk about one cross border case, Tokyo District Court decision, September 5, 2014, Hei23 (wa) no. 13312, Hei24 (wa) no. 31937, 2259 HANREI JIHO [HANJI] 75.

Factual Background

Let's get started with the parties. Plaintiff 1 ("P1") was a female dancer living in New York and her husband Plaintiff 2 ("P2") was a photographer. They got married on February 15, 2010 and P2 lived in Japan but he travelled back and forth between Japan and New York to be with his wife.

Defendant ("D") was a female kimono stylist living in New York since 2008 and her husband worked as a doctor in New York. All parties are Japanese nationals.

P2 and D got to know each other around October 2009 and had an affair in New York, despite being aware of their respective marriages, from May to September 2010 after much corresponding via telephone, emails, and dinners in New York.

P1 became aware of this secret relationship between P2 and D, and P2 admitted such. P1 then sent emails stating that D had had an affair with her husband P2, to D's husband. In response, D also sent emails during September 20 and 25, 2010 to P2's friends living in New York and Japan stating that D did not have an affair with P2 but that P1 only suspected such a relationship and D was annoyed at P1 for visiting D's husband’s office, and P2 suffered from mental illness.

Under these circumstances, P1 sued D at the Tokyo District Court claiming damages under torts on the ground that D and P2 had an affair and caused defamation by sending the emails.

Legal Framework

To analyze the case, I need to consider two basic legal issues, (1) jurisdiction and (2) governing law.

(1) Jurisdiction

This is to determine if you can bring your case to a Japanese court or not. Under the Japanese Civil Procedure Code, for an action relating to a tort, you can bring your case if "the place where the tort took place is located in Japan (excluding cases where the result of a wrongful act committed in a foreign country occurred in Japan, and the occurrence of such result in Japan was ordinarily unforeseeable)" (Article 3-3(viii)).

The court observed with this Article that to have jurisdiction in a Japanese court, it is enough for the plaintiff to prove an objective factual relationship that the defendant's act in Japan caused damage against the plaintiff's legal interest.

As a finding, the court held that the location where the tort based on having affairs took place is New York and denied the jurisdiction of the Tokyo District Court.

On the other hand, with respect to the defamation tort claim, D sent emails to P2's friends including those who lived in Japan so the court held for P1 and acknowledged that if the plaintiff proved an objective factual relationship that the defendant’s act in Japan had caused damages against P’s legal interest then the Japanese court had jurisdiction.

Furthermore, the Civil Procedure Code allows for not only direct jurisdiction, but also indirect jurisdiction, which means if "two or more claims are to be made by a single action, such action may be filed with the court which shall have jurisdiction over one of those claims pursuant to the provisions of Article 4 through the preceding Article" (Article 7).

The court said that if there is a close connection between the claims, a Japanese court has jurisdiction. In this case, the claims over the tort based on having affairs and the defamation were closely connected because a finding regarding the existence of the affair related to the contents of the emails sent by D and affected the amount of damages caused by defamation. 

On this ground, the court found that the Japanese court had jurisdiction over the claims brought by P1.

(2) Governing Law

If the Japanese court had jurisdiction over the claims, it was necessary to decide which laws applied to the case. This concerned governing law. For this issue, we have the Act on General Rules for Application of Laws (Act No.78 of June 21, 2006).

With respect to a tort claim, this Act states that "the formation and effect of a claim arising from a tort shall be governed by the law of the place where the result of the wrongful act occurred; provided, however, that if the occurrence of the result at said place was ordinarily unforeseeable, the law of the place where the wrongful act was committed shall govern" (Article 17).

Also, please note that in relation to defamation tort claims, there is a special provision, which states "Notwithstanding Article 17, the formation and effect of a claim arising from a tort of defamation of others shall be governed by the law of the victim's habitual residence (in cases where the victim is a juridical person or any other association or foundation, the law of its principal place of business)" (Article 19).

Firstly, the court held that the governing law for the tort based on having affairs is New York State law, which does not admit any tort claim based on having affairs. The court found that P1 lived in New York during the time when the love affair occurred and P2 travelled back and forth between Japan and New York so P1’s legal interest relating to their peaceful married life was in New York.  The court rejected P1's claim.

Also, the court found that P1's habitual residence was located in New York so New York state laws applied to the case as well. In the end, the court granted damages of 200,000 JPY based on the defamation by D.


Although fact patterns could be more complex, the important facts concern where a husband and wife are living during married life at the time when an affair occurs, to determine which country has jurisdiction and which laws should apply. People sometimes cross the border. However, if you cross a border in a foreign country, legal analysis could become much more complicated…just like human beings falling in love.