Is it illegal to provide information under the patent linkage system?
Explaining the mechanism of patent linkage and its problems

On October 29, 2025, the lawsuit filed by Nippon Generic against Bayer Yakuhin in the Tokyo District Court (the "Nippon Generic vs. Bayer Case") was dismissed.judgmentThe case concerned whether the provision of information about patent rights by Bayer Yakuhin, a brand-name drug manufacturer, under the so-called "patent linkage system" harmed the business reputation of Nihon Generic, a generic drug manufacturer (Article 2, Paragraph 1, Item 21 of the Unfair Competition Prevention Act).

Regarding whether the provision of information under the patent linkage system constitutes defamation, the Intellectual Property High Court ruled on a similar case on August 13, 2025 (a provisional injunction case filed by Samsung, a generic drug manufacturer, against Regeneron, an original drug manufacturer, known as the "Samsung-Regeneron case").DecideIt has been attracting attention in recent years due to the release of

This article explains the information provision mechanism under the patent linkage system, its problems, and the practical impact of these court cases.

What is the patent linkage system?

What is patent linkage?

Original drugs are usually protected by multiple patents, so even if some of the patents have expired, other patents often remain valid. Therefore, when manufacturing and selling generic drugs, there may be issues with conflicts with the patents of the original drug.
there,In the approval process for the manufacture and sale of generic drugs by pharmaceutical regulatory authorities (Ministry of Health, Labour and Welfare, etc.), a system is in place to determine whether the patent rights of original drugs are infringed. This system is called patent linkage..
Patent linkage is a system that originally began in the United States, but whereas in the United States it is institutionalized based on a special law, in Japan it is handled as an administrative practice based on the so-called "Two Director's Notifications" ("Regarding the Handling of Pharmaceutical Patent Information Related to Approval Review" (Yakushin No. 762, Notification by the Director of the Evaluation Division, Pharmaceutical Affairs Bureau, Ministry of Health and Welfare, October 4, 1994) and "Regarding the Handling of Pharmaceutical Patents Related to Approval Review and Drug Price Listing of Generic Medical Drugs under the Pharmaceutical Affairs Law" (Notification by the Director of the Economic Affairs Division, Health Policy Bureau, Ministry of Health, Labour and Welfare, June 5, 2009, Notification by the Director of the Evaluation and Licensing Division, Pharmaceutical and Food Safety Bureau, Ministry of Health, Labour and Welfare, No. 0605001 and No. 0605014))."If the active ingredient of a brand-name drug is patented and the active ingredient itself cannot be manufactured, the generic drug will not be approved."The government agency's internal standards are stated in the patent linkage document, and based on these standards, it is examined whether generic drugs infringe on the patents of original drugs.

What are the significance and problems of patent linkage?

Patent linkage is of great significance in that it avoids the risk of generic drugs being unable to be supplied in a stable manner due to lawsuits or other disputes arising after the sale of generic drugs, alleging that the patent of the original drug has been infringed.In short, the idea is that it is better to not approve products that are likely to become unmanufacturable or unsaleable due to patent infringement after approval in the first place, in order to ensure a stable supply of pharmaceuticals.
However, this patent linkage system has also been criticized for allowing regulatory authorities to make legal decisions on whether or not a patent right has been infringed, decisions that should be made by a court.
Furthermore, if a generic drug manufacturer is denied approval for a drug due to the risk of patent infringement, it may consider filing an administrative lawsuit against the government (Ministry of Health, Labour and Welfare), but filing a lawsuit against the government (Ministry of Health, Labour and Welfare), which is the body that approves drugs, is not realistic.In that case, it may seem that they should file a lawsuit against the original drug manufacturer to request confirmation that there is no patent infringement prior to drug approval, but past court precedents have not allowed such a lawsuit to be filed.

Is providing information in patent linkage illegal?

The lawsuits introduced at the beginning of this article, the Samsung-Regeneron case and the Japan Generic-Bayer case, were filed under the circumstances described above (Samsung has also filed a similar lawsuit against Bayer Pharmaceuticals, but we will not go into detail about that in this article).

What kind of case is the court case?

In both the Samsung-Regeneron case and the Japan Generic-Bayer case, generic drug manufacturers filed lawsuits alleging that the information provided by original drug manufacturers in patent linkages constituted defamation.
Under patent linkage, when the Ministry of Health, Labour and Welfare checks whether generic drugs infringe on patents, it requests information from the original drug manufacturer, who then responds. In both cases, the original drug manufacturer responded that "there are concerns that generic drugs may infringe on our patents," and the plaintiffs claimed that this response from the original drug manufacturer damaged the generic drug manufacturer's credibility.

How did the court decide?

In both cases, the courts rejected the generic drug manufacturers' arguments and ruled that providing information in patent linkage did not damage the generic drug manufacturers' credibility.The court ruled that the provision of information by the patent holder, a brand-name drug manufacturer, to the Ministry of Health, Labor and Welfare does not constitute defamation of reputation, since it is an act of gathering information prior to administrative action..
This means that it will be virtually impossible for generic drug manufacturers to challenge in court the illegal provision of information by original drug manufacturers, and this is thought to be of great practical significance.

What happens next?

On November 14, 2025, the Ministry of Health, Labour and Welfare announced:In the approval review of generic drugs, when checking whether there are any patent conflicts between original drugs and generic drugs, a system (expert committee system) will be tried out, where opinions from experts can be heard.notificationDidThis expert committee system, taking into account the problems of patent linkage, is intended to reflect the opinions of neutral experts in determining whether or not there is a patent infringement, thereby improving the fairness of the Ministry of Health, Labor and Welfare's judgments.
According to a notice from the Ministry of Health, Labour and Welfare, the written opinions submitted by the expert committee to the Ministry of Health, Labour and Welfare are not legally binding and are not subject to appeal. However, in practice, it is highly likely that the content of the written opinions prepared by the expert committee will have a substantial impact on the final decision on whether or not to approve a drug.

We will continue to pay close attention to whether the expert committee system being trialed this time will produce neutral and fair results.

If you have any questions regarding patents or pharmaceuticals, please feel free to contact Mimura Komatsu Law Office.

【2026.1.13】