Patent enforcement in Japan: Trends and strategies

Japan has traditionally been regarded by some international patent holders as a relatively conservative forum for patent enforcement. Recent statistics and judicial developments, however, suggest that this perception may no longer be accurate. The current litigation environment appears increasingly favourable to patent holders, while recent developments concerning standard essential patents (SEPs) may further enhance Japan’s attractiveness as a forum for patent enforcement.

According to statistics on patent infringement litigation compiled by the intellectual property divisions of the Tokyo District Court and the Osaka District Court for the period from 2016 to 2025, 23% of all cases concluded with a judgment granting the plaintiff’s claims, while another 21% were resolved by settlement containing provisions for injunctive or monetary relief (Statistics on Patent Infringement Litigation [Tokyo District Court and Osaka District Court, 2016-2025]). These figures indicate that 44% of cases were ultimately resolved with some forms of relief for patent holders. Monetary relief was included in about 72% of all settlements, either alone or together with injunctive relief.

The same statistics also indicate that courts upheld a defendant’s patent invalidity defence and found the patent invalid in only 21% of cases concluded by judgment.

A similar tendency can be observed in patent invalidation proceedings before the Japan Patent Office (JPO). In 2023, decisions finding a patent invalid accounted for only 13% of all patent invalidation cases, compared with about 28% in 2016 (Seiko Tamura, director-general of the Trial and Appeal Department at the JPO, “Recent Trends in Trials and Appeals” [25 October 2024]). The figures suggest that patents have become increasingly likely to withstand invalidity challenges.

These developments may be viewed positively by patent holders considering infringement actions in Japan. Conversely, defendants should formulate their strategies with the understanding that successfully challenging the validity of the asserted patent may not be straightforward.

Limitations of patent litigation process

One notable feature of Japanese civil litigation is the absence of both a jury system and a discovery process. Although limited procedures for disclosure of evidence are available, their scope is considerably narrower than discovery in the US. This generally allows litigation costs and duration to remain relatively limited compared with jurisdictions involving extensive discovery.

In a typical first-instance patent infringement action, the parties exchange several rounds of written briefs and documentary evidence (often two or three rounds by each side), followed by court-led settlement discussions and, where necessary, witness examinations. The first-instance proceedings are often concluded within about one-and-a-half to two years, although complex cases may take longer and may involve technical presentation sessions or expert witnesses.

Court submissions must be in Japanese; therefore, foreign-language material must be translated to the extent necessary. Interpretation may also be required for witness examinations or technical presentation sessions.

Court hearings generally involve relatively little substantive oral argument and focus instead on procedural matters and scheduling. Substantive arguments are primarily developed through written briefs and documentary evidence, although oral discussions take place during settlement discussions, witness examinations and technical presentation sessions.

First-instance patent infringement proceedings generally proceed in two stages. The court first considers liability, including infringement and invalidity defence. If infringement is found, the proceedings move to the damages stage. A defendant raising an invalidity defence will also often petition the JPO for a patent invalidation trial, resulting in parallel court and JPO proceedings. Appeals from both district court judgments and JPO decisions are heard by the Intellectual Property High Court in Tokyo.

Japanese patent law also contains several mechanisms designed to assist patent holders in proving damages and obtaining evidence. Article 102 of the Patent Act provides several methods for calculating presumed damages, reducing the patent holder’s burden of proving the amount of loss.

Although Japan does not have US-style discovery, the Patent Act also provides targeted evidence gathering mechanisms. These include: court orders for the production of documents necessary to prove infringement or calculate damages (article 105); expert appraisal procedures for the calculation of damages (article 105-2-11); and an inspection system under which a court-appointed expert may inspect documents, devices or other materials in the possession or control of a party (article 105-2).

These mechanisms can be particularly useful where evidence relevant to infringement or damages is primarily under the defendant’s control.

Japan grants first SEP injunction

In a landmark ruling, the Grand Panel of Japan’s IP High Court denied Samsung’s application for an injunction against an Apple subsidiary for SEP infringement, holding that the claim constituted an abuse of rights. Damages were limited to the fair, reasonable and non-discriminatory (FRAND) royalty rate (IP High Court Grand Panel, 16 May 2014).

The decision’s broad interpretation of abuse of rights and relatively low damages award discouraged SEP owners from litigating in Japan, prompting many to file in jurisdictions offering stronger injunctive relief and higher damages.

Against this backdrop, on 23 June 2025, the Tokyo District Court granted, for the first time in Japan, injunctive relief sought by an SEP owner. The case concerned Pantech’s bid to restrain imports, sales, etc., of Google’s Pixel 7 over long-term evolution (LTE) SEPs. The court found that Google had unreasonably refused to submit a FRAND settlement proposal and was unwilling to obtain a licence on FRAND terms.

Tokyo SEP guidelines speed settlements

Additionally, in January 2026, the Tokyo District Court formulated trial management guidelines specifically tailored to SEPs for both litigation and mediation. The guidelines have attracted considerable attention because they establish a framework that is particularly favourable to SEP owners and enables highly expeditious proceedings. Under these guidelines, the court will recommend settlement at the first hearing, followed by intensive court-facilitated settlement negotiations.

Most notably, the guidelines expressly state that, if the defendant does not voluntarily submit evidence necessary to calculate a global FRAND royalty rate, the court may, in subsequent litigation, find that the defendant is not willing to obtain a licence on FRAND terms.

Accordingly, during settlement negotiations, the plaintiff should emphasise the need for the defendant to produce the necessary material and encourage the court to seek clarification from the defendant, building a factual record favourable to its position. Conversely, the defendant must ensure that its conduct during settlement is not used to its detriment in subsequent litigation.

Japan limits on global FRAND settlement

The guidelines further contemplate that a global FRAND royalty rate may be discussed in settlement. Under Japanese law, courts can determine licence royalty rates only for patents registered in Japan and cannot set a global FRAND royalty rate in a judgment.

In settlement, however, there would appear to be no impediment to facilitating agreement on global FRAND royalties. However, if the defendant is willing to settle the royalty rate for Japanese patents but refuses to negotiate a global licence royalty rate, whether the position may be treated adversely in a judgment raises a sensitive jurisdictional issue.

At the same time, the Tokyo District Court published substantially similar trial management guidelines for SEP judicial mediation. SEP mediation enables the parties to negotiate in non-public proceedings directed by a judge together with attorneys or patent attorneys with SEP expertise. If mediation is unsuccessful, however, the parties must commence fresh litigation before a different judge (Tokyo District Court: “Concerning the Operation of IP Mediation Procedures”). This may make the mediation route circuitous, and commencing litigation from the outset may therefore be more conducive to a swift resolution.

Japan increasingly attractive for SEP owners

Taken together, these developments indicate that the scope for SEP owners to select Japan as a forum has increased significantly. Proceedings under the SEP trial management guidelines may facilitate early agreement on royalty rates in light of the deterrent effect of a potential judgment.