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A patent infringement analysis Yokohama company orders is almost never litigated in Yokohama. Kanagawa Prefecture sits in the Kantō region, and Japan concentrates first-instance patent infringement jurisdiction in just two courts – so a claim brought by a Minato Mirai research centre or a Keihin-zone manufacturer is heard by the Tokyo District Court, roughly forty minutes up the line, before a bench of judges who do nothing else. That single fact reshapes how the analysis has to be built. It must survive a specialist infringement court that will construe the claims narrowly, a parallel validity attack that can run on two tracks at once, and a damages regime rebuilt in 2019. This is what a Yokohama-facing infringement read has to account for.
Where a patent infringement analysis Yokohama case is actually heard
Japan does not spread patent infringement litigation across every district court. Under the Code of Civil Procedure and the Patent Act, first-instance jurisdiction over patent infringement is exclusive to the Tokyo District Court and the Osaka District Court. The dividing line is geographic: the Tokyo District Court hears matters connected to eastern and northern Japan, and the Osaka District Court hears those connected to western and southern Japan.
Yokohama is the flagship city of Kanagawa Prefecture, and Kanagawa is squarely inside the Kantō region in the east. So a Yokohama patentee, and a Yokohama defendant, almost always end up before the Tokyo District Court rather than any court in Kanagawa itself. Yokohama’s own district court handles ordinary civil and criminal work; patent infringement is carved out and sent to Tokyo.
That court is not a general bench that occasionally sees a patent. The Tokyo District Court runs several dedicated intellectual property divisions, staffed by judges who hear technology cases full time and who sit with technical research officials (chosakan) drawn from the Japan Patent Office. A three-judge panel is the norm. For a Yokohama business this is a double-edged advantage: the forum is expert and predictable, but the claim construction is sophisticated and unforgiving, which is exactly why the underlying analysis has to be built to that standard from the first draft.
Appeals: the IP High Court and its Grand Panel
Every appeal from a Tokyo or Osaka District Court infringement judgment goes to one court: the Intellectual Property High Court in Tokyo, established on 1 April 2005 as a special branch of the Tokyo High Court. It also hears appeals against Japan Patent Office trial and appeal decisions, which means the same appellate body reviews both the infringement finding and the validity ruling – a structural feature that keeps Japanese patent law unusually coherent.
The IP High Court sits in four ordinary divisions of three judges each. The most significant cases are heard by the Grand Panel, an enlarged bench of five judges convened to settle points of principle – claim interpretation, the doctrine of equivalents, the calculation of damages. Grand Panel judgments are effectively the guide rails of Japanese patent practice, and they bind the way a District Court will read a claim.
For a Yokohama company this matters at the analysis stage, not just the appeal stage. When we map an accused product onto the claims, we test both literal infringement and infringement under the doctrine of equivalents as the Grand Panel has framed it – the five requirements that flow from the Supreme Court’s Ball Spline decision. An analysis that ignores how the appellate court will ultimately construe the claim is an analysis that wins in the District Court and loses on appeal.
The dual-track validity attack: Article 104-3 and the JPO invalidation trial
The defining feature of Japanese patent enforcement is that validity is fought on two fronts at once, and any infringement analysis that treats validity as an afterthought is dangerous. A defendant in Yokohama has two independent routes to knock the patent out.
- The invalidity defence in the infringement suit — under Article 104-3 of the Patent Act, the defendant argues in the Tokyo District Court itself that the patent should be found invalid, and if the court agrees the patent right cannot be enforced. This flows from the Supreme Court’s 2000 Kilby decision, which held that exercising an obviously invalid patent is an abuse of rights; the 2004 amendment codified it.
- The JPO invalidation trial — separately, the defendant files a request for an invalidation trial (mukou shinpan) with the Japan Patent Office under Article 123, seeking a decision that retroactively extinguishes the patent for everyone, not just the parties.
Because both can run in parallel, a Yokohama patentee can face an Article 104-3 defence and a JPO invalidation trial on the same prior art at the same time, on different timetables. The courts and the JPO coordinate to reduce inconsistent outcomes, but the practical lesson is blunt: a credible patent infringement analysis here is really two analyses stapled together – claim-to-product mapping and a hard-nosed validity and prior-art audit run as if you were the party trying to destroy the patent.
Getting to the evidence: the 2020 inspection (sasho) system
Japan has historically had limited discovery, which made proving infringement of a process or an inside-the-box feature genuinely hard. The 2019 amendment to the Patent Act changed that, introducing an inspection system (sasho / 査証) that came into force on 1 October 2020.
Under the system, once litigation has begun the court can, on petition, appoint a neutral technical expert – typically a patent attorney or academic – to enter the alleged infringer’s premises, inspect equipment and documents, ask questions and run tests, then deliver a report to the court. Confidential-information safeguards are built in. It is closer to a European saisie than to US discovery, but for the first time it gives a Japanese patentee a realistic route to evidence held behind a factory door.
This is directly relevant to Yokohama’s economy. Much of what a Keihin-zone chemical plant or a Minato Mirai R&D centre does is invisible from the outside – a catalyst, a process step, firmware, a materials formulation. Our analysis is built to feed a sasho petition: we identify precisely which claim limitations cannot be confirmed from public information, so the request to the court is targeted and grantable rather than a fishing expedition the court will refuse.
Why Yokohama generates the disputes it does: Minato Mirai, Keihin and the port
Yokohama is Japan’s second-largest city and one of the densest concentrations of corporate research in the country, which is why its patent disputes cluster in a handful of predictable fields.
- Minato Mirai 21 R&D headquarters — the waterfront district houses Nissan’s global headquarters, Murata Manufacturing’s Minato Mirai Innovation Center (opened December 2020, its largest R&D hub in the Kantō region), the Kyocera Minato Mirai Research Center, Shiseido’s global innovation centre, and R&D operations linked to Sony, Fujitsu, Fuji-Xerox and LG. This is where electronics, materials, automotive and cosmetics patents are born – and contested.
- The Keihin Industrial Zone — the belt of heavy industry along Tokyo Bay between Yokohama and Kawasaki is one of Japan’s core chemical and petrochemical clusters, generating process, catalyst and materials patents where infringement is invisible without inspection.
- The Port of Yokohama — one of Japan’s largest ports, a hub for shipping, logistics equipment, container handling and marine engineering, and a point of import where infringing goods are detained.
Each field pulls the analysis in a different direction: a Murata component case turns on measured electrical parameters, a Keihin chemical case on process claims and equivalents, a port-logistics case on mechanical structure and on customs enforcement at the border. We scope the read to the technology, not to a template.
Remedies and the 2019 damages reform
Understanding what a win is worth shapes whether a Yokohama business should sue at all, and the calculus improved for patentees in the same 2019 reform package.
A successful patentee in Japan can obtain a permanent injunction – Japanese courts grant injunctive relief as a matter of course once infringement of a valid patent is established, without the discretionary eBay-style balancing test used in the United States – plus damages and disposal of the infringing goods. Preliminary injunctions are also available. The injunction is frequently the commercial point of the case.
The 2019 amendment revised the damages provisions in Article 102. Previously a patentee’s lost-profits claim was capped at its own production or sales capacity; the reform lets the patentee also recover a reasonable royalty on the infringing sales that exceeded that capacity, and clarifies that the royalty can be assessed on the footing of an infringement having occurred. For a Yokohama SME that cannot itself supply the whole market, that change materially raises the recoverable sum – and a damages model built on the new Article 102 belongs in the analysis, not bolted on after judgment.
How PerspireIP builds the analysis for a Tokyo District Court claim
We work from the granted claims outward, and we build the file so it is ready for a specialist court, a dual-track validity fight and a possible inspection order.
- Element-by-element claim charts mapping each claim limitation onto the accused product or process, argued for both literal infringement and the doctrine of equivalents under the Ball Spline framework the IP High Court applies
- A file-history and estoppel review of the Japanese prosecution, so nothing surrendered during examination at the JPO is claimed back in litigation
- A validity and prior-art audit run adversarially, anticipating both an Article 104-3 defence in the Tokyo District Court and a parallel Article 123 invalidation trial at the JPO
- An evidence map flagging which limitations can only be proven from inside the defendant, so a sasho inspection petition can be drafted tightly enough to be granted
- A damages framing under the revised Article 102, including the royalty on above-capacity sales, so the commercial stakes are clear before filing
- Family-consistent reference numbering across the Japanese, PCT and any foreign counterparts, because inconsistencies invite an argument that the documents describe different inventions
Turnaround is scoped to your deadline – a demand letter, a complaint, or a board decision on whether to sue. Send us the patent number and the accused product and we will confirm scope, price and timing. We do the same work across our Japanese practice, and pair it with prior-art searching where a validity fight is likely.
IP Landscape & Resources in Yokohama
Key intellectual-property authorities and venues relevant to Yokohama:
- Japan Patent Office (JPO) — the national office that examines and grants Japanese patents and conducts invalidation trials under Article 123 of the Patent Act
- Intellectual Property High Court — the Tokyo court with exclusive jurisdiction over patent infringement appeals and appeals from JPO decisions, including Grand Panel rulings
- Courts in Japan (Tokyo District Court) — the judiciary portal for the Tokyo District Court, which holds exclusive first-instance jurisdiction over patent infringement connected to eastern Japan, including Yokohama
- World Intellectual Property Organization (WIPO) — administers the PCT and the treaties behind Japanese patent protection and publishes the international guide to patent case management for judges
Order a Patent Infringement Analysis for Yokohama
Order a Patent Infringement Analysis for Yokohama
Send us the patent number and the accused product or process and we will confirm scope, price and turnaround for a claim chart built for the Tokyo District Court’s IP divisions – with the validity, inspection and damages angles mapped from the start. No obligation, and your files stay confidential.
Explore related PerspireIP services: Patent Infringement Analysis services · IP services in Japan · patent invalidation searches · prior art litigation search · patent portfolio analysis · patent market research.
Frequently Asked Questions
Which court hears a Yokohama patent infringement case?
The Tokyo District Court. Japan gives exclusive first-instance jurisdiction over patent infringement to just two courts – Tokyo for eastern and northern Japan and Osaka for the west and south. Because Yokohama is in Kanagawa Prefecture in the Kantō region, its cases go to the Tokyo District Court’s specialist intellectual property divisions, not to a court in Yokohama itself.
Where do appeals from a Yokohama infringement judgment go?
To the Intellectual Property High Court in Tokyo, established in 2005, which has exclusive jurisdiction over patent infringement appeals and over appeals from Japan Patent Office decisions. The most important points of law are decided by its five-judge Grand Panel, whose rulings guide how the District Court construes claims.
How can a defendant challenge the patent’s validity in Japan?
On two tracks at once. The defendant can raise an invalidity defence in the infringement suit itself under Article 104-3 of the Patent Act, following the Supreme Court’s Kilby decision, and can separately file an invalidation trial with the Japan Patent Office under Article 123. A serious analysis prepares for both.
What is the sasho inspection system?
An evidence-gathering procedure introduced by the 2019 Patent Act amendment and in force since 1 October 2020. After litigation begins, the court can appoint a neutral technical expert to inspect the alleged infringer’s premises, documents and equipment and report back, with confidentiality safeguards – valuable where infringement is hidden inside a Keihin chemical plant or a factory process.
Why is a validity search part of a Yokohama infringement analysis?
Because validity is almost always counter-attacked here, either as an Article 104-3 defence in the Tokyo District Court or as a JPO invalidation trial, or both. We run the prior-art and validity audit adversarially, as if we were the party trying to destroy the patent, so there are no surprises after you file.
What can a Yokohama patentee recover if it wins?
A permanent injunction, which Japanese courts grant as a matter of course once infringement of a valid patent is found, plus damages and disposal of the infringing goods. The 2019 reform to Article 102 lets a patentee also recover a reasonable royalty on infringing sales beyond its own production capacity, raising the recoverable amount.
What kinds of patents does Yokohama typically litigate?
Electronics, materials, automotive and cosmetics from the Minato Mirai 21 R&D headquarters – Nissan, Murata, Kyocera, Shiseido and others – plus chemical and process patents from the Keihin Industrial Zone and shipping, logistics and marine-engineering technology around the Port of Yokohama. We scope each analysis to the specific technology.