An invalidation trial against a key patent: responding, seeking corrections, and assessing the business impact

1 What the patent supports in the business

To decide how to respond and whether to seek a correction, identify the claims being challenged and connect them with the patent's role in the business. An invalidation trial may be requested for individual claims, so the patent as a whole is not necessarily being challenged in the same way.

The patent may serve more than one purpose: excluding competing products from the market, generating licensing revenue, providing exclusivity promised to business partners such as licensees, or supporting future product development. These purposes often overlap rather than being alternatives. Identify which of them the challenged claims support. Where they overlap, decide what to prioritize in defending the patent in this trial. If these considerations are not aligned, even a successful procedural defense may fail to achieve the business objective.

2 Filing a written response and requesting corrections: limits on timing and purpose

Once a copy of the request is served, the chief trial examiner specifies a period for filing a written response. This is also a period during which a correction may be requested.

A request for correction may be made only within specified periods. There are five such periods:

1. The period for filing a written response.
2. A newly specified period for filing a written response after an amendment that changes the gist of the grounds for the invalidation request has been permitted.
3. The period for submitting an opinion after grounds for invalidation have been notified by the trial panel on its own initiative.
4. The period specified in response to an advance notice of the trial decision.
5. A period that the chief trial examiner may specify if a trial decision rejecting the invalidation request has been rescinded by a court judgment and an application is made within one week after that judgment becomes final and binding.

The last of these periods is not granted automatically merely because the judgment rescinding the trial decision has become final and binding.

The permitted purposes of a correction are also limited. There are four:

1. Narrowing the claims.
2. Correcting errors or mistranslations.
3. Clarifying an ambiguous statement.
4. Removing a claim's reference to another claim.

Even where a correction serves one of these purposes, it cannot add subject matter beyond the disclosures in the description and other documents that may provide a basis for the correction. Nor may it substantially broaden or alter the claims.

For each ground for invalidation, consider whether there is a basis for rebutting it, whether a legally permissible correction would resolve it, and whether any issue would remain unresolved. This analysis is the starting point for preparing the response.

3 Enforcing the patent against the products after correction

Whether a correction would overcome a ground for invalidation is not the only consideration. Explanations given in connection with a correction may also be taken into account when interpreting the claims.

Suppose the patent holder explains, to distinguish the invention from prior art, that a particular feature means a component made from a single member and excludes a component made by joining separate members. If the product against which the patent holder seeks enforcement is made from joined members, it becomes harder to adopt an interpretation that includes it when alleging infringement. Statements made in the invalidation trial and in the infringement litigation must be checked for consistency as to the same wording in the same claim. Review them together with explanations previously given during prosecution, decide on the interpretation to advance, and then reassess the other party's products using that interpretation.

Separate two questions in this assessment. First, can the other party's products be assessed as satisfying all the claim limitations after correction, as not satisfying them, or as still requiring investigation? Make this assessment separately for each model, specification, and relevant period. Consider past specifications relevant to a damages claim as well as products currently on sale. Second, if the products are assessed as satisfying the limitations, can the basis for that assessment be proved in court? Identify the evidence for each limitation added or narrowed by the correction. Would an analysis of a physical product be sufficient, or would records held within the other party's business be needed? For evidence not yet available, also assess when it could be obtained.

When a correction narrows a claim, an argument based on the doctrine of equivalents may remain available for a feature that falls outside the literal wording. However, that argument may also be restricted if the feature is regarded as having been deliberately excluded to distinguish the invention from prior art.

Table: points to check when evaluating a proposed response and correction

Issue	Questions to check	Decisions to make
Viability of the arguments and correction	Can the arguments alone defeat the invalidation grounds? Is the proposed correction legally permissible, and would it overcome those grounds?	The approach to the response, whether a correction is needed, and possible corrections.
Consistency of interpretation	Is the explanation distinguishing the invention from prior art consistent with an interpretation covering the other party's products and with earlier explanations?	The interpretation to adopt and the arguments to revise.
Products covered	Does each model, specification, and relevant period satisfy all the corrected claim limitations? Are non-satisfaction and insufficient information distinguished?	Products to retain or remove from the enforcement case, and products requiring further investigation.
Prospects of proof	What evidence establishes the added or narrowed limitations? Can missing evidence be obtained and submitted?	The evidence-gathering approach and whether to adopt the correction.
Effects on the business and contracts	How would the correction affect exclusion of competitors, licensing revenue, promised exclusivity, and future product development? Is notice or consultation required?	The acceptable extent of narrowing and the adjustments and explanations needed.
Timing of decisions and submissions	Can investigation and internal decisions be completed in time for correction opportunities, litigation submissions, and contractual notice deadlines?	When to decide the approach, file submissions, and give notice.

This table presents the firm's approach to organizing the issues. The appropriate response depends on the grounds for invalidation and the substance of the proposed correction.

4 Parallel infringement litigation

The other party may request an invalidation trial while the patent holder is enforcing the patent. In infringement litigation, that party may argue that the patent should be invalidated, and the court hearing the infringement case may also decide that issue.

The court's determination in the litigation operates only between the parties to that case. By contrast, when an invalidation decision becomes final and binding, the patent rights relating to the invalidated claims are, in principle, deemed never to have existed. A final invalidation decision concerning some claims does not automatically extinguish the other claims.

To counter an invalidity defense through correction, the patent holder must, in principle, request correction at the Japan Patent Office and specifically demonstrate in the litigation that the correction is legally permissible, that it resolves the asserted invalidation grounds, and that the other party's products fall within the technical scope of the corrected patent. This is a rejoinder based on correction. It is not necessary to wait until the correction becomes final, and the rejoinder may be available even during a period when a correction request cannot legally be made. Unless exceptional circumstances exist, failure to raise it before the close of oral argument in the fact-finding proceedings prevents the patent holder from challenging the determination on the basis of a correction that later becomes final. Even before that close, the rejoinder may be rejected as an untimely submission.

5 Contracts and communications with external parties

A license agreement may require notice or consultation if the validity of the right is challenged. If exclusive supply or use has been promised to a business partner, check whether that promise can still be fulfilled within the scope narrowed by the correction. If there is a holder of a statutory exclusive license or a pledgee, also check the consent required for the correction request.

Check notice and consultation requirements against the contract, and distinguish confirmed facts from uncertain prospects in any explanation. Disputes over the scope of a license are addressed in Disputes over intellectual property licenses.

6 After the trial decision

An action to rescind the trial decision may be filed within 30 days from the date on which a certified copy of the decision is served. This is a statutory, non-extendable period, although an additional period may be specified for a person in a remote location or a location with poor transport connections. The Intellectual Property High Court hears the action.

The approach to the response and any correction must take into account whether the corrected patent can still be enforced against the products and whether the approach is consistent with the infringement litigation and contractual commitments. We advise on invalidation grounds and proposed corrections, trial proceedings including preparation of written responses, parallel infringement litigation, and actions to rescind trial decisions.

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This article is provided for general informational purposes only and does not constitute legal advice on any specific matter. Please consult us regarding your specific situation. The content is based on the laws and regulations in effect as of the date of the last update.