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Enforcement through the courts


What are the most effective ways for a patent owner to enforce its rights in your jurisdiction?

Patent owners should consider all available enforcement options, including:

  • litigation;
  • border enforcement;
  • negotiation;
  • arbitration; and
  • criminal proceedings (although these are rare).

The best enforcement strategy for a patent owner to pursue will depend on the facts of the case and the patent owner’s business objectives.

What scope is there for forum selection?

The opportunity for forum selection is limited in Japan; thus, it is not a major concern. Infringement cases are heard by either the Tokyo District Court or the Osaka District Court, depending on the location of the defendant’s domicile.


What are the stages in the litigation process leading up to a full trial?

The typical stages in litigation include:

  • the issue of a warning letter by the patent owner or exclusive licensee;
  • the issue of a response letter by the alleged infringer;
  • the issue of a complaint and reply brief;
  • the formal first hearing;
  • subsequent informal preparatory hearings;
  • a determination on infringement;
  • an opportunity for settlement; and
  • a determination of damages.

When the court believes that each party’s case has been clearly presented, it will close the preparatory proceedings and set a date for the oral hearing or trial. During trial, each party presents its case as argued during the preparatory procedure. A panel of three judges will hear the case and, once the case is closed, the court will set a date to issue its decision. Decisions are typically rendered between one and two months after the trial.

How easy is it for defendants to delay proceedings and how can plaintiffs prevent them from doing so?

It is extremely difficult for defendants to delay proceedings, as litigation in Japan is fast. That said, defendants can prolong proceedings by increasing the number of issues that the court must address. For example, a defendant can allege that the patent’s subject matter is invalid on multiple grounds or request an invalidity hearing during trial. Plaintiffs can respond by requesting that the allegations be dismissed by arguing that they were made only to delay the proceedings.

How might a party challenge the validity of a patent through the courts in anticipation of a potential suit for infringement being issued against it?

In anticipation of an infringement suit, a party may request that the court issue a declaratory judgment for the non-applicability of the patent, which means that the court will determine whether:

  • the defendant’s conduct infringed the claimed scope of the patent;
  • the patent is valid per the formality requirements; and
  • the plaintiff is the valid patent owner.

In addition, a potential defendant may request a declaratory judgment for right of prior use, if applicable.

During an infringement suit, a party can challenge the validity of a patent as a defence. However, any court decision regarding validity is binding only on the parties to the dispute.

At trial

What level of expertise can a patent owner expect from the courts?

While Japan has 50 district courts, the Tokyo and Osaka District Courts hear all technology-related cases, as they have expertise in this field. The Tokyo District Court has four divisions that specialise in IP cases. The Osaka District Court has two specialised IP divisions. The IP High Court has sole jurisdiction over appeals of Tokyo and Osaka District Court patent decisions.

The district courts and the IP High Court work with research officials who assist them in understanding the technical details of a dispute. Research officials are technical experts and experienced patent examiners from the Patent Office.

The courts have a joint list of experts from which they can appoint expert commissioners in patent cases. This list consists of:

  • professors (64%);
  • patent attorneys (16%);
  • researchers at public institutions (10%); and
  • researchers at private institutions (10%).

Expert commissioners work on a part-time basis, under two-year commitments. They assist judges in understanding the technology involved in each patent case.

Are cases decided by one judge, a panel of judges or a jury?

Patent infringement cases are decided by a panel of three judges at the district court level.

If jury trials do exist, what is the process for deciding whether a case should be put to a jury?

Jury trials are not available for patent cases in Japan.

What role can and do expert witnesses play in proceedings?

Court-appointed experts provide a formal opinion on specific issues raised by the court and can be questioned during the trial. Court-appointed experts first submit a written report, after which judges ask supplementary questions. Thereafter, both parties can question the expert.

Parties usually appoint their own experts. Party experts submit written opinions to the court as documentary evidence and are questioned before the court. While these experts are not court appointed, they can play an important role in complex cases.

The courts have a joint list of experts from which they appoint expert commissioners. While expert commissioners help judges to understand the technology involved in each patent case, they cannot be questioned or cross-examined formally in open court or at trial. Expert commissioners usually do not appear in court. They can question both parties, but the parties cannot question them.

Does your jurisdiction apply a doctrine of equivalents and, if so, how?

In 1997 the Supreme Court endorsed the doctrine of equivalents for the first time in Tsubakimoto Seiko Co Ltd v THK KK. The Supreme Court set out five factors for an accused product or process to be considered infringing under the doctrine of equivalents:

  • The equivalent element cannot be an essential part of the claimed invention. The burden of proof is on the patent owner.
  • The accused product or process must have the same object and effect as the claimed invention (ie, it must provide the same function and result as the patented product or process). The burden of proof is on the patent owner.
  • Someone skilled in the art should have been able to substitute the claimed element with the equivalent element in the accused device in view of the state of the art at the time of infringement. The burden of proof is on the patent owner.
  • The accused product must not be anticipated or obvious in view of the prior art.
  • There must be no prosecution history estoppel.

In 1998, the Supreme Court declared that even if – within the construction as indicated in the patent specification – there is a feature which differs from the patented invention, the product will be considered identical and fall within the technical scope of the patented invention if:

  • the different feature is not essential to the patented invention;
  • the purpose of the patented invention can be achieved by replacing the feature with a feature from the patented invention, resulting in an identical function and effect;
  • a person with average knowledge of the state of the art could have easily suggested such replacement at the time of production of the products;
  • neither product was identical to the technology in the public domain at the time when the patented invention was applied for, and neither product could easily have been conceived at that time by a person with average knowledge of the state of the art; and
  • there were no special circumstances (eg, the products were intentionally excluded from the scope of the patent claim in the application process). 

Is it possible to obtain preliminary injunctions? If so, under what circumstances?

When quick injunctive relief is required, a patent owner can request a preliminary injunction. Preliminary injunctions can be obtained in prima facie infringements if there is prima facie evidence of irreparable harm and proof that an immediate remedy is needed. In Japan, court proceedings for preliminary injunctions are separate from those for damages and permanent injunctions. To obtain a preliminary injunction, a patent owner must establish that:

  • it is the rightful owner or exclusive licensee;
  • the infringer is commercially manufacturing, using, selling or offering to sell the infringing product;
  • the infringing activities are covered by the scope of the patent claims; and
  • an injunction is necessary to avoid irreparable damages.

In addition, the district courts often require plaintiffs to provide a security deposit before injunctive relief is issued. The amount of the security deposit depends on the facts of the case. Generally, security deposits are calculated based on the amount of profits that the alleged infringer is expected to lose due to the injunction and the cost of imposing the injunction (eg, the cost of storing the banned import).

How are issues around infringement and validity treated in your jurisdiction?

Infringement is generally addressed in court proceedings, through negotiation or in some cases arbitration. The Patent Office generally hears invalidity claims. While invalidity claims can also be heard by the courts, any court decision on validity is binding only on the parties to the dispute.

Will courts consider decisions in cases involving similar issues from other jurisdictions?

Judges may find decisions involving similar issues from other jurisdiction to be persuasive, but they are not binding.

Damages and remedies

Can the successful party obtain costs from the losing party?

The successful party may obtain court costs; however, the successful party is not entitled to obtain attorneys’ fees from the losing party.

What are the typical remedies granted to a successful plaintiff?

Typical remedies granted to a successful plaintiff include injunctions and damages awards. Successful plaintiffs are typically entitled to permanent injunctions against the infringing defendant’s use of the invention until the patent expires, as provided for by the Patent Act. Damages are calculated on the basis of a reasonable royalty or lost profits. Infringers may be liable for damages equivalent to royalty as far back as the date of publication of the patent application in Japan.

In cases regarding patent validity, a decision may be rendered regarding the grant or invalidation of a patent, depending on the subject of the claim. Such decisions are binding as to the parties of interest.

How are damages awards calculated? Are punitive damages available?

Damages awards are calculated on the basis of a reasonable royalty or lost profits. Three articles of the Patent Act provide the basis for calculating damages:

  • Article 102(1) – lost profits based on the number of infringing products sold, multiplied by the patent owner's profits per unit;
  • Article 102(2) – lost profits based on the assumption that the infringer's profits will be the amount of damages awarded; and
  • Article 102(3) – reasonable royalty.

Under Article 105(1) of the Patent Act, a patent owner can file a motion with the district court to compel an infringer to produce the documents needed in order to determine damages. Infringers may be liable for damages equivalent to royalty as far back as the date of publication of the patent application in Japan. For this to occur, Article 65 of the Patent Act requires the patent owner to prove that:

  • it provided actual notice to the infringer of the pending patent application; or
  • the infringer knew of the published patent application, yet continued its infringement.

How common is it for courts to grant permanent injunctions to successful plaintiffs and under what circumstances will they do this?

The courts will grant permanent injunctions to successful plaintiffs in almost all cases. The Patent Act specifically provides for injunctions. Actual damage, intent and negligence are not required for injunctions to be issued. Thus, the courts will likely issue permanent injunctions where infringement is found. Statistically, the courts rule in favour of the plaintiff 23% of the time.

Timescale and costs

How long does it take to obtain a decision at first instance and is it possible to expedite this process?

Most first-instance cases are decided between a year and a year and a half from the date of filing the complaint to the rendering of a decision. These proceedings generally cannot be expedited.

How much should a litigant plan to pay to take a case through to a first-instance decision?

The amount that a litigant should budget depends on the value of the case. For example, if a litigant is being sued for Y100 million, it can expect to pay Y300,000 in court fees and Y10 million in attorneys’ fees (Y2.7 million up front and Y7.3 million as remuneration).

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