Major Patent Litigation and Regulatory Developments in Japan from 2021 to June 2026
Akihiro Ryuka
Patent Attorney (Japan) / Attorney-at-Law (California)
A. Scope of the Survey
This report covers patent-related decisions rendered by Japanese courts from 2021 through June 2026, focusing on cases in the following criteria:
● Cases in which a patentee’s claim for an injunction or damages was granted, at least in part
● Cases in the fields of electrical engineering, information and communications technology, software, semiconductor manufacturing equipment, or machinery
● Cases involving a foreign corporation or foreign corporate group as a party
● Cases involving standard-essential patents (SEPs)
● Cases presenting rulings of practical significance regarding patent validity or grounds for invalidity
B. Major Cases in Which Injunctions or Damages Were Granted
● Patentee: Pantech Corporation (Korean corporation)
● Defendant: Google Godo Kaisha (U.S.-affiliated company)
● Tokyo D. Ct., June 23, 2025
● Remedy: Injunction against the transfer, offer for transfer, and importation of the accused products
● Patent: No. 6401224 (an LTE standard-essential patent)
Case Overview
The patent at issue relates to technology for mapping the Physical Hybrid ARQ Indicator Channel (PHICH) — transmitted by a base station in LTE communications — onto OFDM symbols.
The Tokyo District Court enjoined the transfer, offer for transfer, and importation of Google smartphones. The judgment permitted provisional execution on condition that the plaintiff post a bond of JPY 10 million.
FRAND Determination
Because a FRAND declaration had been made with respect to the patent at issue, the question arose whether an injunction claim based on a standard-essential patent constituted an abuse of rights.
The court examined the defendant’s conduct during licensing negotiations and concluded that the defendant could not be regarded as a willing licensee negotiating in good faith under FRAND terms. Accordingly, the court did not treat the injunction claim as an abuse of rights.
Practical Significance
This decision is a significant published precedent in which an injunction was granted in Japan based on a FRAND-declared standard-essential patent.
It demonstrates that merely stating a willingness to accept a license on FRAND terms is not sufficient; courts will assess the actual conduct of the negotiations, including the following factors:
● Timely responses to license proposals
● Willingness to enter into a non-disclosure agreement
● Provision of sales and other information needed to calculate royalties
● Presentation of reasonable counterproposals
● Response to settlement proposals from the court
● A genuine intent to actually conclude a license agreement
Note: This case might have been appealed.
● Patentee: Pantech Corporation (Korean corporation)
● Defendant: ASUS JAPAN K.K. (a member of the Taiwan-based ASUS group)
● Tokyo D. Ct., April 10, 2025
● Remedy: Damages equivalent to a FRAND royalty:
● Injunction/Destruction: Dismissed
● Patents: Nos. 4982653 and 5694479 (LTE standard-essential patents)
Case Overview
Pantech alleged that smartphones imported and sold by ASUS JAPAN, including the ROG Phone and Zenfone series, infringed patents relating to PHICH mapping technology in LTE.
The plaintiff sought an injunction against importation, transfer, and other acts involving the accused products, together with destruction of the products and an award of damages.
The court found infringement of some of the patents and ordered damages equivalent to a FRAND royalty, but did not grant the requested injunction or destruction order.
Calculation of the FRAND Royalty
The court calculated the royalty equivalent for the patents at issue using, in essence, the following top-down methodology:
●１．Using the sales revenue of the accused products as the starting point for the calculation.
●２．Setting an aggregate royalty rate for the LTE or 5G standard as a whole.
●３．Apportioning the aggregate royalty among the number of standard-essential patents declared for the LTE standard.
●４．Reflecting factors such as the number of patents at issue and the period of use.
The judgment specifically examined the aggregate royalty rate and the number of standard-essential patents applicable to the LTE standard.
Practical Significance
This decision is a recent, important example of a Japanese court specifically calculating a FRAND royalty for a standard-essential patent.
Although both cases involved the same LTE standard-essential patents held by Pantech, an injunction was granted in the Google case, whereas only damages were awarded in the ASUS case. This difference illustrates that an implementer’s negotiating conduct and willingness to take a license significantly affect whether an injunction will be granted.
Note: This case might have been appealed.
Transmission of a Program from an Overseas Server into Japan
● Patentee: Dwango Co., Ltd.
● Defendant: FC2, Inc. (U.S. corporation) and others
● IP High Ct., July 20, 2022
● Remedy: Injunction and damages
● Patent: Nos. 4734471, 4695583
Case Overview
Dwango held a patent relating to, among other things, a program for controlling the overlap of user comments displayed on video content.
FC2 transmitted the program from servers located in the United States to user terminals located in Japan.
The issue was whether such transmission could be characterized as “providing” the program within Japan, even though the originating server was located outside Japan.
The IP High Court held that, rather than looking solely at the location of the originating server, the series of acts should be assessed substantively as a whole, and found that the conduct constituted “providing” the program within Japan. The court accordingly granted an injunction and awarded damages.
Practical Significance
The decision made clear that merely locating a server outside Japan does not avoid infringement of a Japanese patent.
For software, SaaS, and cloud services directed at Japan, the following factors are important:
● Whether the recipient of the program is located in Japan
● Whether the program is installed on a terminal located in Japan
● Whether the program’s principal functions are used within Japan
● Whether the effects of the invention are realized within Japan
● Whether the service is directed at the Japanese market
“Production” of a Network System Comprising an Overseas Server
●Patentee: Dwango Co., Ltd.
●Defendant: FC2, Inc. (U.S. corporation) and others
●IP High Ct. Grand Panel, May 26, 2023
●Supreme Ct., March 3, 2025
●Remedy: Injunction and damages
Case Overview
This case concerned a cross-border system in which the servers constituting a video-comment distribution system were located in the United States while the user terminals were located in Japan.
The IP High Court Grand Panel held that, even where some of the constituent elements of a system are located outside Japan, infringement of a Japanese patent may be established if the series of acts, viewed as a whole, can be characterized as the “production” of the system within Japan.
In reaching this conclusion, the court comprehensively considered the following factors:
●The location of each constituent element of the system
●Where the acts leading to completion of the system took place
●Where the system’s principal functions are performed
●Where the effects of the invention manifest
●The impact on the economic interests of the Japanese patentee
Practical Significance
This decision has significant implications for internationally distributed systems, such as the following:
● Cloud computing
● SaaS
● AI inference services
● IoT systems
● Systems comprising overseas servers and domestic terminals
● Platforms with processing functions distributed across multiple countries
At the time of filing, it is advisable to prepare not only claims directed to the system as a whole, but also claims that can be satisfied by elements located within Japan or by the acts of a single actor.
5. Hamamatsu Photonics v. Tokyo Seimitsu Case
Laser Processing Technology for Semiconductor Wafers
● Patentee: Hamamatsu Photonics K.K.
● Defendant: Tokyo Seimitsu Co., Ltd.
● Tokyo D. Ct., December 15, 2022
● IP High Ct., April 24, 2024
● Full text of the Tokyo District Court judgment
Case Overview
Hamamatsu Photonics held a patent relating to so-called “stealth dicing” technology, in which a laser beam is focused inside a semiconductor wafer to form a modified region, and the wafer is then divided starting from that modified region.
Tokyo Seimitsu manufactured and sold laser dicing equipment, including the ML200 and ML300 series.
The Tokyo District Court found infringement with respect to some of the equipment and ordered an injunction, destruction of the infringing equipment, and damages of approximately JPY 1,506,970,000.
Appellate Decision
On April 24, 2024, the IP High Court revisited the degree to which the patented invention contributed to the product as a whole, as well as the method for calculating damages under Article 102 of the Patent Act (which provides that the infringer’s profit is presumed to be the patentee’s lost profit). On that basis, the court modified the damages portion of the first-instance judgment and ordered Tokyo Seimitsu to pay JPY 831,916,753 plus delay damages.
Practical Significance
This case is significant for the following reasons:
● The degree of the patented invention’s contribution to the product as a whole was examined in detail
● The damages calculated under Article 102 of the Patent Act were substantially revised on appeal
6. Chair-Type Massage Machine Case
●Patentee: Family INADA
●Defendant: Fuji Medical Devices
●IP High Ct. Grand Panel, October 20, 2022
●Remedy: JPY 391,549,273 plus delay damages
●Patents: Nos. 4504690 and 4866978
●English-language version of the judgment
Case Overview
The patents at issue related to, among other things, a forearm-treatment mechanism provided in the armrest of a chair-type massage machine. The first-instance court denied the plaintiff’s claims, but the IP High Court Grand Panel found infringement with respect to some of the defendant’s products and ordered damages of approximately JPY 392 million.
Calculation of Damages
The court held that where the patentee sells products competing with those of the infringer, the occurrence of damage sufficient to support the application of Article 102, paragraph 2 of the Patent Act may be recognized. It further held that even where the presumption under that paragraph — that the infringer’s profit constitutes the patentee’s lost profit — is partially rebutted, the patentee may additionally claim, for that portion, damages equivalent to a reasonable royalty under paragraph 3 of the same article.
In particular, the court awarded a reasonable royalty even for the portion of infringing products exported to foreign markets where the patentee’s own products were not sold, on the ground that the patentee could have licensed a third party in those markets.
Practical Significance
Even where infringing products are exported abroad, and a portion of them does not directly compete with the patentee’s own products, a reasonable royalty may still be claimed for that portion.
● Plaintiff: Future Eye Inc.
● Defendant: LINE Corporation
● Tokyo D. Ct., May 19, 2021
● Remedy: Damages awarded in part
Case Overview
The Tokyo District Court affirmed the inventive step and validity of the patent at issue, and found that the “Furufuru” feature infringed the patent and caused damage.
Calculation of Damages
As the “Furufuru” feature was provided for free, the plaintiff argued that multiple revenue streams associated with LINE’s services should form the basis for calculating damages.
The court excluded revenue from friend registration via QR code or ID search, account advertising, LINE Out, and similar services from the basis for calculating damages, on the ground that such revenue either had no relationship to the “Furufuru” feature or only an indirect and remote one. However, the court affirmed the damage caused by the services associated with the “Furufuru” feature.
Practical Significance
Even a free software feature can give rise to damages if a causal connection can be established with related advertising revenue, paid-service revenue, or other service revenue.
At the same time, the revenue of an entire platform cannot automatically be used as the basis for calculating damages; the extent to which the infringing feature contributed to each revenue stream must be specifically proven.
C. Significant Rulings on Patent Invalidity and Validity
● Plaintiff: Tokyo Seimitsu Co., Ltd.
● Patentee: Hamamatsu Photonics K.K.
● IP High Ct., November 29, 2022
● Conclusion: Tokyo Seimitsu’s claim to rescind the JPO decision was dismissed
● Patent: No. 3867108
Overview
Tokyo Seimitsu filed a request for an invalidation trial against Hamamatsu Photonics’ laser processing equipment patent, disputing inventive step, clarity, the support requirement, and the enablement requirement, among other issues.
The JPO permitted the patentee to correct the patent and then held the invalidation request unfounded; the IP High Court upheld that decision.
Practical Significance
In Japan, even where invalidity is raised as a defense in an infringement action, the patentee may concurrently narrow and correct the claims before the JPO in order to keep the patent valid. This case underscores the importance, where necessary, of a strategy that combines an infringement action with a Correction Trial (or a request for correction made in an invalidation trial) to clarify the distinction over the prior art while keeping the accused product within the technical scope of the patent.
2. Restriction on Enforcement Due to Violation of the Support Requirement
● Patentee: Harada Industry Co., Ltd.
● Defendant: Yokowo Co., Ltd.
● IP High Court, December 1, 2020
● Patent: No. 5237617 (antenna device)
● Relief Sought: Claims for an injunction, destruction of infringing products, and damages based on patent infringement were dismissed (affirming the first-instance decision)
Overview
The IP High Court examined whether a person skilled in the art could recognize, from the working examples, test results, and technical explanations set forth in the specification, that the problem to be solved could be resolved across the entire scope of the invention encompassed by the claims. The court concluded that the claims did not satisfy the support requirement and were therefore subject to a ground for invalidity, and held that the patent could not be enforced.
Where the scope of the claims is generalized beyond what is disclosed in the specification, the claims may violate the support requirement under Article 36, paragraph 6, item 1 of the Patent Act, and enforcement of the patent may accordingly be restricted under Article 104-3.
Practical Significance
A description supporting the full scope of the claims is particularly important for the following types of inventions:
● Inventions defined by numerical limitations
● Parameter inventions
● Material inventions
● Inventions broadly defined in functional terms
● Inventions in which a broad generic concept is extracted from only a small number of working examples
The specification should preferably describe multiple working examples, comparative examples, the basis for any numerical ranges, and the technical mechanism by which the problem is solved.
D. Recent Statutory Amendments and Institutional Changes
1. Third-Party Opinion Solicitation System in Patent Infringement Litigation
The 2021 (Reiwa 3) amendment to the Patent Act introduced a system for soliciting opinions from third parties in patent infringement litigation. Where the court considers it necessary, it may solicit opinions from members of the public on legal or technical matters relevant to the case.
This system was used for the first time in the IP High Court Grand Panel proceedings in the Dwango v. FC2 case. Going forward, the system may be used in cases with significant social or industrial impact, such as those involving:
● Cloud- and AI-related patents
● Standard-essential patents
● Cross-border patent infringement
● Platform-related inventions
● Patents in cutting-edge technology fields
2. Relaxation of the Requirements for Reinstatement of Rights
The 2021 amendment relaxed the requirements for reinstating rights after missing certain statutory procedural deadlines, changing the standard from the previous requirement of a “legitimate reason” to, in principle, a standard based on the absence of intent (i.e., the failure not having been intentional).
Procedures that may be eligible include:
● Applications claiming priority
● National phase entry of PCT applications
● Requests for examination
● Payment of patent (annuity) fees
● Other procedures required to be performed within certain statutory periods
That said, a request for reinstatement is subject to a time limit and a reinstatement fee, and not every missed deadline will be excused.
3. Consolidation of the Damages Calculation Framework
The damages-calculation provisions introduced by the 2019 amendment to the Patent Act took effect in 2020. Recent decisions increasingly reflect the strengthened approach to protecting patentees introduced by that amendment.
Article 102 (Presumption, etc. of Amount of Damage)
(1) Where a patentee or an exclusive licensee claims against a person who has intentionally or negligently infringed the patent right or exclusive license compensation for damage sustained as a result of the infringement, and that person has assigned articles that constitute the act of infringement, the amount of damage sustained by the patentee or exclusive licensee may be calculated as the sum of the following amounts:
(i) the amount obtained by multiplying the per-unit profit that the patentee or exclusive licensee would have earned had there been no such act of infringement, by the quantity of articles assigned by the infringer (the “assigned quantity”), up to the quantity not exceeding the amount corresponding to the patentee’s or exclusive licensee’s capacity to work the patent (the “workable quantity”) — and, where there are circumstances under which the patentee or exclusive licensee would have been unable to sell all or part of that quantity, after deducting the quantity corresponding to such circumstances (the “specific quantity”);
(ii) where the assigned quantity exceeds the workable quantity, or where a specific quantity exists (except where it is not found that the patentee or exclusive licensee could have granted an exclusive license or a non-exclusive license under the patent right or exclusive license), the amount of money the patentee or exclusive licensee would have been entitled to receive for working the patented invention corresponding to that patent right or exclusive license, corresponding to such excess quantity or specific quantity.
(2) Where a patentee or an exclusive licensee claims against a person who has intentionally or negligently infringed the patent right or exclusive license compensation for damage sustained as a result of the infringement, and that person has earned a profit from the act of infringement, the amount of that profit shall be presumed to be the amount of damage sustained by the patentee or exclusive licensee.
(3) A patentee or an exclusive licensee may claim, against a person who has intentionally or negligently infringed the patent right or exclusive license, an amount of money equivalent to what the patentee or exclusive licensee would have been entitled to receive for the working of the patented invention, as the amount of damage sustained.
(4) In determining, under paragraph (1), item (ii) and the preceding paragraph, the amount of money equivalent to what would have been received for working the patented invention, the court may take into account the amount that the patentee or exclusive licensee would have obtained as consideration for working the patented invention pertaining to that patent right or exclusive license, on the premise that the patentee or exclusive licensee had reached an agreement with the infringer on the assumption that such infringement had occurred.
(5) Paragraph (3) shall not preclude a claim for damages exceeding the amount set forth in that paragraph. In such a case, where the person who infringed the patent right or exclusive license was not guilty of intent or gross negligence, the court may take that fact into consideration in determining the amount of damages.
4. Online Trial Proceedings
The 2021 amendment also put in place a framework enabling parties and their representatives to participate online in oral hearings conducted as part of JPO trial proceedings.
This is practically beneficial for foreign companies, as it expands the possibility of participating in oral hearings without traveling to Japan.
E. Trends Observed in Recent Decisions
1. Injunctions Remain an Important Remedy
In Japan, once infringement and the validity of a patent are established, the patentee may, in principle, seek an injunction to stop or prevent the infringing acts. Recent cases have resulted in injunctions against the following:
● Google smartphones
● FC2’s video-comment distribution service
● Programs transmitted from overseas servers into Japan
● Systems comprising overseas servers and domestic terminals
● Laser processing equipment for semiconductor wafers
2. The Scope of Enforcement of Japanese Patent Rights Against Foreign Companies Is Expanding
The Pantech v. Google case, the Pantech v. ASUS case, and the Dwango v. FC2 cases all directly involved a foreign corporation or foreign corporate group. Even where a manufacturing base or server is located outside Japan, infringement of a Japanese patent may still be established where any of the following circumstances is present:
● The product is imported into Japan
● The product is sold, or offered for sale, within Japan
● A program is transmitted to a terminal located in Japan
● A system is formed by users located in Japan
● The invention’s principal function or effect is realized within Japan
● A service is provided targeting the Japanese market
3. Damages Awards May Increase
Recent cases have resulted in the following damages awards:
● Hamamatsu Photonics v. Tokyo Seimitsu: approximately JPY 832 million on appeal
● Chair-Type Massage Machine case: approximately JPY 392 million
● Standard-essential patent cases: an amount equivalent to a FRAND royalty
● Software cases: damages calculated based on revenue associated with the infringing feature
Punitive damages are not available in Japan, but substantial damages awards remain possible based on factors such as the technical value of the patented invention, its degree of contribution to the infringing product, the infringer’s profit, and a reasonable royalty rate.
4. Injunctions May Be Available Even for Standard-Essential Patents
The Pantech v. Google case demonstrated that an injunction may be granted even with respect to a FRAND-declared standard-essential patent, where the implementer is found not to have negotiated a license in good faith. By contrast, in the Pantech v. ASUS case, no injunction was granted, and only damages equivalent to a FRAND royalty were awarded.
Accordingly, in SEP cases, what matters is not only whether the patent at issue is in fact standard-essential, but the entire course of the licensing negotiations.
F. Implications for Patent Filing Strategy in Japan
1. Software and Cloud Fields
It is advisable to draft claims combining the following categories:
● System claims having both servers and user terminals
● Program claims
● Server claims
● User terminal claims, or the claims that can be satisfied by a device located within Japan
● Information processing method claims
2. Machinery and Semiconductor Manufacturing Equipment Fields
It is advisable to consider the following claims:
●Claims to the completed apparatus
● Claims to principal modules and components
● Control method claims
● Manufacturing method claims
● Claims to replacement parts and consumables
● Claims to dedicated products directed at indirect infringement
3. Telecommunications and Standards-Related Fields
● Clarify the correspondence between the standard specification and the claim elements
● Draft claims for which infringement can readily be proven by reference to standard documents
● Prepare claims in each of the terminal, base station, method, and program categories
● Properly manage standard-essentiality and FRAND declarations
● Keep detailed records of licensing negotiations
● Present infringement notices, claim charts, and license proposals in a timely manner
4. Support in the Specification
To maintain broad claims, a person skilled in the art must be able to understand, from the specification as filed, that the problem to be solved can be resolved across the full scope of the claims. The specification should, to the extent possible, describe the following:
The relationship between the problem to be solved and each claim element
● Multiple working examples
● Comparative examples
● The basis for any numerical ranges
● The technical mechanism of operation
● Alternative structures or materials
● Why the effect extends across the entire scope of the claims
