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  • 執筆者の写真York Faulkner

A Brief Overview of Patent Litigation in Japan


Japanese patent law is largely similar to the substantive law in the United States. Procedurally, however, patent litigation in Japanese courts is quite different with notable absences of U.S. style discovery and a U.S. form of trial by jury.

The Courts. Historically, issues of patent infringement were ponderously litigated in the courts, and questions about patent validity were reserved exclusively for “invalidity trials” conducted in the Japanese Patent Office. A lot has changed in recent years. The Supreme Court of Japan has affirmed the ability of the courts to entertain patent invalidity as a type of defense in an infringement action, authorizing the courts to refuse to enforce patents that are clearly invalid. Patent litigation has been substantially streamlined, resulting in a Japanese “rocket docket.”

Patent infringement suits must be brought either in Osaka District Court or Tokyo District Court—where specialized technical advisors are available to assist those courts in litigation. The district courts determine infringement and, where found, also conduct damages trials. Time to resolution is typically less than one year.

Japanese courts have not always been so efficient in adjudicating patent infringement matters. In fact, during the 1990s, the average time to resolution among Japan’s fifty district courts was a ponderous thirty-one months. In the early 2000s, Japan instituted substantial changes to the way in which patent infringement actions are adjudicated in the Japanese courts and to the manner in which patent invalidation proceedings are conducted before the Board of Appeals of the Japanese Patent Office.

Beginning in 2003, the Tokyo and Osaka District Courts were given exclusive jurisdiction over trials of patent infringement matters with the objective of developing special technical and legal expertise by consolidating patent infringement trials in those courts. The Tokyo District Court has jurisdiction over matters arising in “eastern” Japan, including the judicial districts within the jurisdiction of the Tokyo, Nagoya, Sendai, and Sapporo High Courts. The Osaka District Court has jurisdiction over cases arising in “western” Japan, including the judicial districts within the jurisdiction of the Hiroshima, Fukuoka, and Takamatsu High Courts. The judges are assisted by full-time technical advisors who have specialized scientific and technical backgrounds. The technical advisors are most commonly hired from the patent examiner ranks at the JPO. In addition to the full-time technical advisors, the Supreme Court may appoint “expert commissioners” to assist the district courts as neutral advisors in especially complex cases. The expert commissioners are often university professors who have advanced technical abilities without any particular connection to industry.

In April 2005, a specialized branch of the Tokyo High Court was established as the Intellectual Property High Court. The Intellectual Property High Court, or “IP High Court” as it has become known, exercises exclusive jurisdiction over appeals from the Tokyo and Osaka District Courts as well as appeals from the JPO, including final claim rejections in patent applications and final rulings in patent invalidation trials. The IP High Court has substantially raised the stature of patent litigation in Japan while shortening the time for appeals to roughly 6-9 months. The Supreme Court of Japan is the court of last resort and hears appeals, at its own discretion, arising from the IP High Court.

The Patent Office. Although a defense of patent invalidity may be asserted in district court litigation, a patent is not finally and conclusively declared invalid until a panel of administrative judges at the Japanese Patent Office have so ruled in a formal procedure called a “patent invalidity trial.” Japan’s Patent Act specifies the rules for initiating patent invalidity trials and the grounds for declaring a patent invalid.

Customs Office Import Suspension Proceedings. Similar to remedies available before the U.S. International Trade Commission, intellectual property owners can initiate proceedings before the Japanese Customs Office and ask the Director General of Customs to determine if goods intended for import into Japan or intended for export from Japan infringe intellectual property rights. In making that determination, the Director General of Customs may seek technical assistance from disinterested experts as well as from the Commissioner of the Patent Office. Where a determination of infringement is made, the Director General of Customs has broad powers to confiscate and destroy the offending goods.

Patent Infringement Trials in the Tokyo and Osaka District Courts

A patent infringement “trial” in Japan’s Tokyo and Osaka District Courts is not a single event as in the United States and other countries. Instead, the trial consists of a series of briefings and hearings before a three-judge panel. A patent infringement action is initiated by filing a complaint. By comparison to U.S. standards, the pleading requirements in Japan are strict, requiring the “specific conditions” of the alleged infringement which includes a detailed comparison of the patent claim elements to the accused product or process. The complaint is filed with the district court together with the filing fee, which can be quite substantial depending upon the amount of the asserted damages. Under Article 104-2 of Japan’s Patent Act, the accused infringer is required to “clarify the specific conditions of his/her act” in denying the infringement claim. Under Article 105 of the Patent Act, the parties may be ordered to produce the evidence that they rely upon to either assert or deny infringement and damages.

After completion of the pleading stage of the case, the trial procedure begins which, generally speaking, constitutes a series of written briefings and hearings before the court, which are scheduled every one or two months. With input from the parties, the district court panel identifies the factual and legal issues to be briefed by the parties in advance of each hearing. Oral testimony is rarely requested at the hearings. However, the parties commonly offer expert opinion and analysis by written submission with their briefs.

This sequence of briefing and hearing continues until the court is satisfied that no significant factual or legal issues remain open or unaddressed, and the court is prepared to enter judgment. In practice, the district court ordinarily conducts its inquiry in two phases, focusing first on the alleged infringement and defenses. If the court finds infringement, then a second phase of briefings and hearings are conducted on damages issues. Throughout the proceedings, the court is often very active in encouraging and mediating settlement, especially where the briefings and hearings have revealed potentially dispositive evidence or resulted in significant threshold rulings.

Although issues of patent validity had traditionally been creatures of JPO proceedings, the Supreme Court ruled in its April 11, 2000 TI v. Fujitsu decision that the district courts may entertain and rule upon a defense of patent invalidity. Article 104-3 of the Patent Act was subsequently enacted, authorizing the district courts to refuse to enforce patents that are clearly invalid. Nevertheless, a district court ruling on patent invalidity is enforceable only between the parties to the litigation. Final adjudication of the patent’s validity is reserved for the JPO.

Appeals to the Japanese IP High Court

The IP High Court has exclusive jurisdiction over appeals from patent matters adjudicated before the Tokyo and Osaka District Courts and matters before the JPO, including final claim rejections and patent invalidity trials. Ordinarily, appeals are briefed and heard before a panel of three judges. However, the IP High Court may form a “Grand Panel” of five judges to hear cases with significant precedential impact on industry or society. Appeals before the IP High Court are de novo, and under certain circumstances, the court may entertain new evidence not previously submitted to the district court. The appeal proceeds much in the same way as trial before the district course, as a series of briefings and hearings that continue until the court is prepared to rule.

Appeals to the Japanese Supreme Court

Appeals to the Supreme Court are generally limited in number and in scope. Appeals raising constitutional questions are made as a matter of right. In addition, the Supreme Court may accept appeals in cases that raise significant procedural or substantive issues that merit its review.



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