Intellectual Property

Responding to pharmaceutical patent disputes

The issues to consider in pharmaceutical patent disputes depend on the stage at which the dispute arises and whose acts are being challenged. An allegation of infringement of a process patent during development and an application for a provisional disposition (interim injunction) to stop sales immediately before launch involve different deadlines, materials to collect, and decisions to make.

In pharmaceutical patent disputes, approval and supply schedules may intersect with issues involving patent term extensions, working a patented invention for experimental or research purposes, contract manufacturing, and joint research. In addition to interpreting the claims, the review involves checking the details of the approval, the acts actually carried out, and their relationship with the contracts.

This page provides links to articles on different scenarios involving pharmaceutical patent disputes and sets out matters that require repeated consideration across those scenarios. For individual procedures and the criteria applied, please see the relevant articles.

Reviewed by Keishi Yoshikawa, Attorney at Law and Patent Attorney (Dai-Ichi Tokyo Bar Association)

Last updated: September 27, 2026

What to check first

The types of documents received (a warning letter, an application, a summons to a hearing, or an order already issued), response deadlines and hearing dates, and relevant contractual notification obligations and deadlines
The numbers and claims of the patents being asserted, and whether a patent term extension has been registered
The acts being challenged (manufacturing, transfer, offers of transfer, importation, or use of a process) and the parties carrying them out

How we can helpIdentifying which scenario a matter falls within and directing it to the relevant articles / Considering technical scope separately from the scope of the effect of an extended patent right / Reviewing whether testing and manufacturing for clinical trials or approval applications constitute working a patented invention for experimental or research purposes / Mapping the acts of the commissioning company, contractor, and API supplier against the claims / Considering grounds for invalidating patents and patent term extension registrations / Reviewing and negotiating the terms of joint research agreements, contract manufacturing agreements, and license agreements

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Contents

1 Articles by scenario
2 Matters to check at each business stage
3 Matters to check across scenarios
4 Companies facing claims and patent holders
How we can assist
Frequently asked questions

If an order has already been issued, the response differs from that at the application stage. We first check whether any steps are needed following issuance, including whether to seek a stay of enforcement.

1 Articles by scenario

Even where an inquiry is described simply as involving an allegation of patent infringement, the approach depends on the scenario. The following is not an exhaustive list of pharmaceutical patent disputes; it identifies the scenarios for which we have prepared individual articles.

Responding to a provisional disposition (interim injunction) to stop pharmaceutical sales immediately before launch — Where an application for a provisional disposition to stop sales has been filed, or may be filed, in relation to a pharmaceutical product scheduled for launch.

Injunctions based on pharmaceutical patents with extended terms: responses by companies facing claims and by patent holders — Where an injunction is sought based on a patent with an extended term, or where enforcement of such a patent is being considered.

Responding to patent infringement allegations concerning testing and manufacturing for clinical trials or approval applications — Where allegations concern testing or manufacturing for clinical trials or approval applications.

Responding to patent infringement allegations concerning API supply and contract manufacturing — Where allegations concern the supply of an API (active pharmaceutical ingredient) or contract manufacturing. This is relevant to commissioning companies, contract manufacturers, and API suppliers.

Responding when a joint research partner's consent to licensing a jointly owned patent cannot be obtained — Where a company intends to license a jointly owned patent to a third party but cannot obtain its joint research partner's consent.

More than one article may be relevant to a single matter. A provisional disposition sought immediately before launch based on a patent with an extended term involves both the article on provisional dispositions and the article on patents with extended terms. Allegations concerning the supply or contract manufacturing of an API for testing involve both the article on API supply and contract manufacturing and the article on testing for clinical trials or approval applications. The frequently asked questions at the end of this page explain how to approach these articles.

For the stage before a dispute arises, we have separate articles, currently available in Japanese only, on setting the terms of use needed for commercialization before agreeing in a joint development agreement that results will be jointly owned, and on deciding whether to patent manufacturing technology or keep it confidential. Responding when invalidation proceedings are brought against a company's own patent before the Japan Patent Office (JPO) is also covered in a separate article available in Japanese only.

We also advise on situations in which the other party's manufacturing process is unknown, raising issues about whether infringement has occurred and how to secure evidence; situations in which allegations involving a third party's patent during joint research halt research or out-licensing; and situations in which approval review or NHI drug price listing schedules proceed alongside civil enforcement of patent rights. We plan to prepare separate articles on these issues over time.

2 Matters to check at each business stage

The responses available in a pharmaceutical patent dispute depend on the stage between development and sales at which the dispute comes to light. The following table sets out matters to check at each business stage.

Stage	Matters to check at this stage	Points requiring a decision
Joint research and joint development	Ownership of the results; arrangements for licensing to third parties if ownership is shared; terms for using existing technology	Whether the joint research partner's consent can be obtained when licensing a jointly owned patent to a third party
Establishing the manufacturing process and formulation	Whether to file a patent application or keep the technology confidential; creation of records supporting a prior use right	Whether the company can prove when it worked the invention if infringement of a process patent is alleged
Testing for clinical trials or approval applications	The purpose of the tests being conducted and the quantities needed; correspondence between the test plan and manufacturing records	Whether the activities remained within the scope necessary for the approval application
API procurement and contract manufacturing	Correspondence between the claims and the process steps handled by each company; the scope of the commissioning company's license	Whether the contractor or supplier may face separate liability for its acts
Approval applications and changes to approved matters	The scope of testing and manufacturing while an application is pending; the category of procedure applicable to changes to approved matters	Whether the timetable for addressing the patent issues aligns with the pharmaceutical regulatory procedures
Immediately before launch	Results of searches concerning other companies' patents; the impact on supply if an injunction is issued	Whether to maintain or change the launch schedule
After sales begin	Actual sales and supply activities; the products and periods concerned; inventory and planned shipments; whether claims have been made concerning past acts	Whether to continue supply; how to respond to claims concerning past manufacturing and sales; how to explain the situation to business partners

3 Matters to check across scenarios

Even when the scenarios differ, pharmaceutical patent disputes repeatedly require the same checks. Reviewing these four matters early in a consultation can help identify the range of materials to collect.

3-1 Whether working the invention is permissible under patent law, and pharmaceutical regulatory procedures

We examine the patent law issues and the pharmaceutical regulatory procedures separately. For changes to approved matters, the Act on Securing Quality, Efficacy and Safety of Products Including Pharmaceuticals and Medical Devices (the "PMD Act") specifies cases in which approval for a partial change is required and cases in which notification of a minor change is sufficient. Which category applies to a change in the manufacturing process or API supplier depends on the nature of the change. Where changes to approved matters require pharmaceutical regulatory procedures, the type of procedure and the time required may make it necessary to revise the supply schedule. We also distinguish between the schedules for approval and NHI drug price listing procedures and those for negotiations between the parties and court proceedings.

3-2 Reviewing technical scope and the scope of the effect of an extended patent right

The Patent Act provides that the technical scope of a patented invention is determined based on the claims attached to the application. For a patent right whose term has been extended on the basis of an approval decision, however, the Patent Act contains a separate provision. The Act provides that the effect of the extended patent right does not extend to acts other than working the patented invention with respect to the product covered by the approval decision underlying the extension (where that decision specifies a particular use for the product, the product used for that particular use). The analysis presupposes that the product in question falls within the technical scope of the claims, but that alone does not mean that the patent right extends to acts during the extension period granted on the basis of the approval decision. The extent to which differences between the product covered by the approval decision and the product in question fall within the effect of the extended patent right is addressed in Injunctions based on pharmaceutical patents with extended terms.

3-3 Testing and manufacturing for approval applications, and manufacturing in preparation for sales

The Patent Act provides that a patent right does not extend to working a patented invention for experimental or research purposes. The Supreme Court has held that conducting tests during the patent term that are necessary to obtain materials to accompany an approval application, and producing and using a product covered by the patented invention for those tests, with the aim of manufacturing and selling a generic drug after the patent expires, constitutes working a patented invention for experimental or research purposes. The same judgment states that acts such as producing generic drugs during the patent term for transfer after expiration, beyond the scope necessary for testing for an approval application, constitute patent infringement and are not permitted. Accordingly, neither the label "for testing" nor the existence of an intention to sell the product in the future is sufficient on its own to determine the outcome. The question of which tests and which acts require consideration is addressed in Testing and manufacturing for clinical trials or approval applications.

3-4 Each company's acts of working the invention, and contractual licenses and allocation of responsibility

For a product invention, the Patent Act defines working the invention to include production, use, transfer and similar transactions, export, import, and offers of transfer and similar transactions. Production, use, transfer, and importation are distinct acts. Pharmaceutical manufacturing and supply involve commissioning companies, contract manufacturers, API suppliers, and clinical trial contractors. An assessment of the commissioning company's acts does not, by itself, lead to the same conclusion for contractors or suppliers. Whether there are acts deemed to constitute infringement even where there is no direct infringement, how far the commissioning company's license extends, and how to address contractual indemnities and notification obligations are separate questions. The distinctions between individual acts are addressed in API supply and contract manufacturing, while the different treatment of a company's own working of an invention and licensing to third parties is addressed in Licensing a jointly owned patent.

4 Companies facing claims and patent holders

Even for the same issue, the matters to check first differ between the company facing a claim and the patent holder. However, the issues to consider, depending on the circumstances, are common to both sides.

Technical scope — The company facing the claim considers how to develop its argument that the product or process falls outside the technical scope, while the patent holder considers the prospects of arguing and proving that it falls within that scope.
Scope of the effect of the extended patent right — Both sides check the details of the approval decision underlying the extension and the differences between the product covered by that decision and the product in question.
Working a patented invention for experimental or research purposes — Both sides check the purpose of the tests and the relationship between the nature and quantities of the acts carried out and the necessary testing. The company facing the claim considers how to explain why its acts constitute working a patented invention for experimental or research purposes, while the patent holder considers the prospects of rebutting that explanation.
Grounds for invalidation — In infringement litigation, the Patent Act provides that a patent holder is not entitled to enforce the right against the opposing party if the court finds that the patent should be invalidated in patent invalidation proceedings, or that the extension registration should be invalidated in invalidation proceedings for a patent term extension registration. The company facing the claim therefore considers how to develop its arguments, while the patent holder considers the prospects of rebutting them.

A party applying for a provisional disposition must make a prima facie showing of both the right to be preserved and the need for provisional relief. The fact that the proceedings concern a provisional disposition does not dispense with the need to explain the alleged infringement in concrete terms. If notifying business partners is being considered, the content and scope of the notice need to be decided carefully. Communicating or disseminating false statements of fact that harm the business reputation of a competitor constitutes unfair competition under the Unfair Competition Prevention Act.

How we can assist

We check the contents of the documents received and clarify the deadlines and the company's internal response arrangements.
We separately review technical scope, the scope of the effect of the extended patent right, and working a patented invention for experimental or research purposes.
We review the correspondence between each company's acts and the claims, and identify which issues concern which company.
We consider the scope of the investigation and how to develop arguments concerning grounds for invalidating patents and patent term extension registrations.
We assist with provisional disposition and litigation proceedings and prepare response letters and warning letters.
We review the legal issues and organize the information needed for decisions on continuing supply, changing processes or suppliers, and explaining the situation to business partners.
We review the terms of joint research agreements, contract manufacturing agreements, and license agreements, and assist with negotiations and the preparation of agreements.

Frequently asked questions

Q1 An application for a provisional disposition has been filed against a company immediately before launch based on a patent with an extended term. Which article should the company read first?

The deadlines need to be checked first, so please see Responding to a provisional disposition (interim injunction) to stop pharmaceutical sales immediately before launch for the types of documents, deadlines, and course of the proceedings. The assessment of the scope of the patent right's effect is addressed in Injunctions based on pharmaceutical patents with extended terms. Addressing the provisional disposition proceedings does not, by itself, complete the assessment of the scope of the effect of the extended patent right.

Q2 A company undertakes contract manufacturing of an API for use in clinical trials. Which articles are relevant?

Responding to patent infringement allegations concerning API supply and contract manufacturing addresses the correspondence between the company's acts and the claims, while Testing and manufacturing for clinical trials or approval applications addresses the scope of working an invention for experimental purposes. The conclusion that a patent right does not extend to the commissioning company's acts is a separate question from whether the same conclusion applies to the acts of a contractor or API supplier.

Q3 What should be checked if manufacturing takes place overseas?

The Patent Act also defines importation as an act of working an invention. The place of manufacturing alone does not determine the conclusion. Each act needs to be checked to establish what is being done, where, and by whom. Please also see Responding to patent infringement allegations concerning API supply and contract manufacturing.

Contact

Making an inquiry

You may consult us on pharmaceutical patent disputes, from identifying the scenario involved to reviewing technical scope and the scope of the effect of the extended patent right, clarifying each company's acts, and responding to proceedings. If you bring the documents received, the numbers of the patents concerned, and materials showing your company's development and approval stage, we can begin considering the specifics at the initial consultation.