Joint strategies for patent infringement and invalidation proceedings

Patent invalidation and infringement proceedings together constitute a patent dispute resolution mechanism.

The patent invalidation proceedings may determine the basis of the rights in the patent infringement proceedings and directly affect the progress and result of the patent infringement proceedings.

The patent infringement proceedings may, in turn, affect the scope of protection of the claims, thereby affecting the result of the patent invalidation proceedings.

Since the patent invalidation and infringement proceedings are closely related to and affect each other, patentees must consider the two proceedings jointly to obtain a desired result of rights protection. The positions in both proceedings must be consistent.

Patent invalidation proceedings

In patent invalidation proceedings, the patentee attaches importance to the doctrine of estoppel. When making an amendment or a statement, the patentee should be careful to prevent the scope of protection from failing to cover the alleged infringing product owing to improper abandonment of a technical solution.

In the patent invalidation proceedings, the patentee often interprets the claims in a manner that narrows their scope of protection to maintain the patent validity. In contrast, in the patent infringement proceedings, the patentee often interprets the claims in a manner that expands the scope of protection to cover the alleged infringing product as much as possible.

To ensure the consistency of the scope of protection of the claims and maintain the public’s trust, the patent system adopts the doctrine of estoppel to prevent the patentee from making different statements in different proceedings and benefiting from both sides.

Application of doctrine of estoppel in China

Relevant Chinese judicial interpretations provide for the doctrine of estoppel; in other words, a technical solution abandoned by the patent applicant or patentee through an amendment or a statement in the patent grant or invalidation proceedings shall not be included in the scope of protection of the patent in the patent infringement proceedings, unless the amendment or statement was explicitly denied.

Since this is only a provision in principle, there are many controversies regarding the understanding and application of the doctrine of estoppel in judicial practice. The focus of the controversies lies in how to understand the concepts of abandoning a technical solution and explicit denial.

The patentee should be the subject of the abandonment action. In Zhongyu Electronics v Jiuying Electronic Technology, the Supreme People’s Court (SPC) held that abandonment under the doctrine of estoppel is usually self-abandonment by the patentee through an amendment or a statement.

If the China National Intellectual Property Administration (CNIPA) maintains a patent right that is valid on the basis of only a dependent claim rather than an independent claim on which the dependent claim depends, when judging whether it constitutes abandonment under the doctrine of estoppel, attention should be paid to whether the abandonment is made by the patentee, and the criteria for determining abandonment must be strict. A scenario in which the independent claim is declared to be invalid does not definitively result in the application of the doctrine of estoppel.

Adding a technical feature does not mean that the patentee abandons all technical features equivalent to the added technical feature. In Zhejiang Freeride Chemical v Tianjin Lianli Chemical, the SPC held that although adding a technical feature in a claim would further define the scope of protection of the patent, if there is no other evidence proving that the patentee had abandoned a specific technical solution through an amendment or a statement, it cannot be concluded that the patentee had completely abandoned all technical features equivalent to the added technical feature only for the reason that adding the technical feature narrowed the scope of protection of the claims. This interpretation is of great significance as it eliminates patentees’ common concerns when amending the claims in invalidation proceedings.

The abandoned technical solution must be determined in consideration of the patentee’s statement and the defects to be overcome by the amendment to the claims. In Nanjing Changjiang Industrial Furnace Technology v Yangzhou Dicastal Wheel Manufacturing, the SPC held that, regarding the added technical feature “the lifting driving oil cylinder . . . at the top of the supporting frame”, the applicant emphasised in the statement that the “supporting frame” of the patent differed from the “quenched lifting frame” of reference one and did not define nor emphasise the “top”. The court, therefore, held that the doctrine of estoppel should not be applied to exclude the technical solutions in which the lifting driving oil cylinder was not installed at the “top” of the support frame.

If the technical feature is added to overcome the defect of lacking inventive step, the court will analyse which technical element in the technical feature that is emphasised by the patentee contributes to the prior art. It will then determine the abandoned technical solution.

Regarding the concept of explicit denial, in Cao Guilan et al v Chongqing Lifan Automobile Sales, the SPC held that the patent examination department did not accept the statement that a certain technical feature was not common knowledge during the prosecution proceedings and explicitly gave a rejection opinion. Moreover, the grant of the patent was not based on a restrictive statement regarding that technical feature.

Since the restrictive statement made by the patentee was explicitly denied in the substantive examination, and the invalidation proceedings did not reach an opposing conclusion, the patentee’s restrictive statement was determined to be explicitly denied.

Whether the statement is explicitly denied is determined by comprehensive consideration of both the prosecution and the invalidation proceedings. If the examiners or judges reject the patentee’s restrictive statement, based on which the statement does not lead to the grant of the patent application or maintenance of the patent right, the conditions for explicit denial will be deemed to be satisfied. Explicit denial does not include scenarios in which the examiners or judges are non-committal.

Suggestions for patent invalidation proceedings

Considering that the doctrine of estoppel has a limit on the scope of protection of claims, the patentee should take care to ensure that the alleged infringing product will still be covered when abandoning a technical solution or making an amendment or a statement in invalidation proceedings.

Although explicit denial can limit the application of the doctrine of estoppel, examiners do not often comment on the patentee’s restrictive statement. It is, therefore, not easy to satisfy the conditions of explicit denial.

To take the initiative in both proceedings, the following suggestions are advised.

Only make amendments that help maintain patent validity

An amendment that does not substantively help to maintain patent validity should not be made in patent invalidation proceedings. For example, if an independent claim is likely to be invalidated, and a dependent claim thereof may remain valid, and the additional technical feature of the dependent claim is a specific concept corresponding to the general concept in the independent claim, the patentee should not voluntarily delete the independent claim and upgrade the dependent claim to be a new independent claim. This is because if the independent claim is declared invalid by the CNIPA without the above amendment, the doctrine of estoppel will not apply as the patentee has not self-abandoned the technical solution; on the contrary, if the patentee voluntarily makes the amendment, the doctrine of estoppel may be applied, and the doctrine of equivalents may not be applied to the specific concept.

Select distinguishing features carefully

If the patent contains several technical features that distinguish it from the prior art, the patentee should comprehensively consider the prior art and the technical solution of the alleged infringing product when arguing inventive step, and it should focus its argument on some of, rather than all, the technical features. For example, consider a situation in which the claim has distinguishing technical features C, D and E over the prior art, the prior art has the technical features C1, D1 and E1, and the infringing product has the technical features C, D and E1 (C1, D1 and E1 being variants of C, D and E, respectively). In this scenario, the patentee should emphasise the contribution to the prior art of the distinguishing features C and D in the alleged infringing product, and of features C and D (rather than E) in the claim; otherwise, if the patentee focuses its claim on all the technical features (C, D and E) as being important to the contribution to the prior art, the judge will consider the patentee to have abandoned its claim regarding feature E1, therefore resulting in the infringing product not being covered by the scope of protection of the claim for equivalent infringement.

Be specific

In the invalidation proceedings, when overcoming the defect of lacking inventive step by adding a technical feature, a statement should be made only for the technical element in the technical feature that contributes to inventive step, in view of the fact that the added technical feature may also include other technical elements that do not contribute to inventive step. If the argument for inventive step is too general, the doctrine of equivalents may not be applied to the other technical elements in the infringement proceedings.

Examine defects carefully

The patentee should carefully handle defects that have been pointed out by the petitioner. Although the possibility of invalidating the patent owing to formal defects is relatively low in practice, if the patentee tries to overcome the defects by making a statement, it may limit the patent’s scope of protection and affect the infringement proceedings.

Patent infringement proceedings

In the patent infringement proceedings, the patentee should keep the patent invalidation proceedings in mind and interpret the claims in a manner that prevents adverse effects on the stability of the patent right.

Provisions and application of the doctrine of reverse estoppel

Article 3 of the Provisions (I) of the SPC on Several Issues concerning the Application of Law in the Trial of Administrative Cases Involving the Grant and Confirmation of Patents provides that:

A people’s court may, when defining terms in the claims in an administrative case involving the confirmation of a patent, refer to the patentee’s relevant statements that have been adopted by an effective judgment of a civil case involving patent infringement.

This provision is often known as the doctrine of reverse estoppel, based on which a patentee’s statement in the patent infringement proceedings may affect the determination of the scope of protection of the claims in the patent invalidation proceedings.

The premise for applying the doctrine of reverse estoppel is that the patentee’s statement has been accepted by the judgment document, and the judgment document has come into effect.

In the administrative proceedings of CNIPA v VMI Netherlands and Sachi Intelligent Equipment, the SPC held that even if it is deemed necessary to refer to the relevant statements of the patentee in the civil infringement case, since the first-instance civil judgment has not come into effect, the relevant statements and opinions of the patentee accepted in the ineffective judgment shall not serve as a reference.

Consequently, even if the patentee makes a statement in the patent infringement proceedings that is inconsistent with that in the invalidation proceedings, the doctrine of reverse estoppel cannot be applied if the statement is not accepted by an effective judgment.

Suggestions for patent infringement proceedings

Although the application of the doctrine of reverse estoppel is relatively strict, once applied it may affect the basis of the rights in the patent invalidation proceedings; therefore, the patentee should be careful when making statements in the patent infringement proceedings and reasonably interpret the scope of protection of the claims.

Since there is no limit to the time or frequency for initiating invalidation proceedings, the defendant can file an invalidation petition against the patent even after the infringement judgment has come into effect.

To prevent the defendant from successfully invalidating the patent based on the doctrine of reverse estoppel, when interpreting the claims in the patent infringement proceedings, the patentee should comprehensively consider the alleged infringing product, the ongoing patent invalidation proceedings and the potential subsequent invalidation proceedings, and interpret the scope of protection of the claims to a limited extent in respect of the alleged infringing product.

Selecting an agency for patent invalidation and infringement proceedings

Patent invalidation and infringement proceedings involve complex technical and legal issues; thus, it is crucial to select a suitable agency to obtain a favourable result.

In practice, some patentees may engage a patent agency to handle the patent invalidation proceedings and engage a law firm to handle the patent infringement proceedings. This may incur potential risks.

Owing to the different objectives of the two proceedings, engaging with two agencies that act separately may be detrimental to the coordination of the proceedings and increase the communication costs.

For example, if the agency handling the patent invalidation proceedings does not participate in the patent infringement proceedings, it may lack in-depth understanding of the technical solution of the alleged infringing product and be unable to fully consider the mutual influence between the two proceedings. Consequently, to distinguish the patent from the prior art and maintain the patent validity, the agency handling the patent invalidation proceedings may make more restrictive amendments and interpretations to the claims, which may result in application of the doctrine of estoppel and bring adverse effects to the patent infringement proceedings.

To ensure the strict consistency of the positions in the two proceedings, the patentee must pay particular attention to the interaction between the two proceedings to keep the two agencies coordinated. This may also increase communication costs.

From the perspective of practice, it is preferable to engage one law firm to handle both the patent invalidation and infringement proceedings to seek a balance between the two proceedings and ensure that all positions are consistent so that the patent infringement proceedings can be successfully concluded; however, this strategy also sets higher requirements regarding the expertise of the law firm. Nevertheless, in recent years, patentees, including multinationals, have increasingly turned to this strategy.

Strategy against abuse of invalidation proceedings to delay infringement proceedings

To substantively affect the patent infringement proceedings, the defendant may file an application to suspend the trial on the basis of the patent invalidation proceedings to procedurally delay the patent infringement proceedings and prolong the litigation period.

To prevent the defendant from intentionally delaying the infringement proceedings, the plaintiff may take the following measures:

  • The patentee may select a stable patent as the basis of the right. For a utility model patent, a positive patent right evaluation report should be obtained before filing the patent infringement proceedings.
  • During the patent infringement proceedings, it is advisable to submit an expert report or appraisal opinion to the court, which may prove the strong stability of the patent.
  • The patentee may apply for a temporary injunction from the court before or during the patent infringement proceedings. Once the injunction is obtained, the infringement can be stopped in time.

Comment

The patent infringement and invalidation proceedings are strongly related and must be connected to ensure consistency. This can be ensured by determining the scope of protection of the claims as a point of connection between the two proceedings.

The patentee should determine an appropriate scope of protection by comprehensively considering the doctrines of estoppel and reverse estoppel, and retaining the same strategy in both the proceedings. Engaging with one law firm to handle both the patent invalidation and infringement proceedings can ensure consistency of the positions.

Finally, to efficiently proceed with the patent infringement proceedings, the patentee should take measures to prevent the defendant from intentionally delaying the patent infringement proceedings.

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