Prosecution History Estoppel
ILegal Basis
In order to balance the interest of the patentee and the interest of the social public, the patent system provides the doctrine of estoppel to prevent the patentee from presenting contradictory statements and thereby gaining at both ends.
The Chinese Patent Law does not explicitly stipulate the doctrine of estoppel. In reviewing infringement cases, the court mainly judges based on the following judicial interpretations:
The Supreme People’s Court introduced the doctrine of estoppel for the first time into China’s patent system by Article 6 of
Interpretation by the Supreme People’s Court on Some Issues Concerning the Application of Laws to the Trial of Patent Infringement Disputes (Judicial Interpretation (2009) No. 21) (hereinafter referred to as “Infringement Interpretation I”): Where the patent applicant or patentee has abandoned a technical solution through amendment to claims and/or specification or observations during the prosecution or invalidation process, if the patentee asserts in a patent infringement lawsuit that the extent of protection of the patent right should include said technical solution, the People’s Court shall not support such assertion of the patentee.
The Supreme People’s Court further specified the concept of “abandoned a technical solution” in Article 13 of
Interpretation by the Supreme People’s Court on Some Issues Concerning the Application of Laws to the Trial of Patent Infringement Disputes (Judicial Interpretation (2016) No. 1) (hereinafter referred to as “Infringement Interpretation II”): “Where the right holder proves that the restrictive amendments or statements to the Claim set, Description and appended Drawings by the patent applicant or the patentee are definitely denied in the procedures of patent granting and patent right verification, the courts shall find that such amendments or statements do not cause the abandonment of the technical solution.”
Beijing High People’s Court provided refined provisions on the doctrine of estoppel in Articles 61 to 64 of
Guidelines for Patent Infringement Determination (2017). Article 61 defines “estoppel”; Article 62 specifies the purpose or the grounds for restriction or partial abandonment of the protection scope; Article 63 refines the standard for determining recorded or negated restrictive amendments or observations; and Article 64 specifies the premise and the burden of proof for application of estoppel. Due to limited space, the specific contents of these articles are omitted herein.
Considering the legal force, Infringement Interpretation Iand Infringement Interpretation IIare legal provisions and are universally applicable; while
Guidelines for Patent Infringement Determination is the guiding proposals of a local court, providing a reference for the local courts.
IIJudicial Cases of the Supreme People’s Court
The legal rules and provisions are abstract and not vivid. Described below are some cases judged by the Supreme People’s Court in the latest two years involving the doctrine of estoppel, so that the readers may have more intuitive impression on the doctrine as well as its application.
1. (2022) Supreme Court IP Civil Final No. 905
The Supreme People’s Court opines that: in the invalidation declaration procedure, Chugai Pharmaceutical Co Ltd. incorporated a part of the additional technical feature of original claim 2 into claim 1 to restrict the antioxidant of claim 1 as dl-α-tocopherol and cancelled original claim 2, and correspondingly altered the numerals and the dependencies of the other claims. The above amendment is in fact abandonment of the technical solution of original claim 1, remaining one of the coordinate technical solutions of original claim 2, so that the scope of protection of the independent claim is changed from a solution of using any one of the antioxidants to a solution of using only dl-α-tocopherol. In addition, the description of the involved patent listed various antioxidants including dl-α-tocopherol, ***, etc. Referring to the disclosure of the description and all history amendments to the claims, Chugai Pharmaceutical Co Ltd. has clearly selected a particular technical solution to be protected by amending the claims, which is a unique antioxidant among the four antioxidants as coordinate solutions of original dependent claim 2. This further indicates that Chugai Pharmaceutical had the specific and clear intension to abandon the solution of the specific antioxidant *** by the amendment. Chugai Pharmaceutical Co Ltd. neither provided reasonable explanation for the technical solution of using *** as the antioxidant which was abandoned upon the amendment nor stated that the amendment did not affect the validity of the patent right. In fact, Chugai Pharmaceutical stated that the above amendment was made in order to overcome the defect of not being supported by the description. Chugai Pharmaceutical Co Ltd. did not state justified reasons or provide the proof proving that the technical solution of other antioxidants was not abandoned by amending the claims. Accordingly, the doctrine of estoppel should apply in this case; and the technical solution of using *** as the antioxidant should not be included in the scope of protection of the subject patent right.
2. (2020) Supreme Court IP Civil Final No. 541
The Supreme People’s Court opines that: by amending claim 1 of the subject patent, the patentee restricts the positional relationship between the automatic feeding machine and the hydraulic station in the brick molding press is “on the same side”. The published application documents of the subject patent did not define the structure of the brick molding press, the attachment position of the robot palletizer and the automatic feeding machine, or the function and effect of the automatic feeding machine. In order to be granted a patent right, the patentee amended claim 1 according to the office opinions of the CNIPA by incorporating the technical feature of original claim 3, including the attachment position of the automatic feeding machine, into claim 1, which is a restricting amendment. Claim 1 as amended specifies that the automatic feeding machine is mounted “on the same side” with the hydraulic station in the brick molding press. It should be deemed and foreseen that the technical solution of they being arranged on different sides is abandoned. According to the doctrine of estoppel, the technical solution of the automatic feeding machine and the hydraulic station in the brick molding press in the positional relation of on different sides should not be included in the scope of protection of the subject patent; nor should the feature in question be interpreted to the extravagant extent to be equivalent to “on the same side”.
3. (2021) Supreme Court IP Civil Final No. 935
The Supreme People’s Court opines that: the claims of the subject patent did not define the attachment direction of the floor brush and the rotation direction of the floor brush during operation. Although Sonatech stated in the first Office Action and in the examination procedure for invalidation declaration of the subject patent that the attachment direction of the floor brush and the rotation direction of the floor brush during operation are the same due to the mating operation of the block and the slot. The statement of the patentee that the attachment direction of the floor brush and the rotation direction of the floor brush during operation are the same according to the subject patent was merely an example of the engagement relationship between the block and the slot. The patentee did not mention the technical means for a case in which the attachment direction and the rotation direction were opposite, i.e., the block and the slot are not in an engaged state, or a technical solution that is not claimed by the subject patent. In addition, the statement of Sonatech that the attachment direction of the floor brush and the rotation direction of the floor brush during operation are the same was not accepted in the invalidation procedure. That is, the subject patent right remained valid not based on this statement of Sonatech. Therefore, the above statement of Sonatech presented in the granting and post grant procedures does not narrow down the scope of protection.
The above Cases 1 and 2 are typical application scenarios of the doctrine of estoppel, with restriction or partial abandonment of the protection scope by the patent applicant or patentee being required for overcoming such substantial defects as lack of novelty or inventiveness, lack of essential technical features, lack of support of the claims by the description and insufficient disclosure of the description, which render an application unpatentable
[i], and indeed the subject patent (applicant) being granted or maintained based on the amendments or statements restricting the scope of protection. In Case 3, the Supreme Court specified that where a statement of the patentee made in the post grant procedure is not accepted, and the related patent was not granted or maintained based on such statement, such statement does not have a restricting effect on the scope of protection of the patent right. Further, the judgments in Cases 1 and 3 also inspired the strategy based on the article of “definitely denied” of Infringement Interpretation II; that is, the patentee or applicant may argue that the amendments to the patent documents were not made to overcome substantial defects which render the application unpatentable, or prove that the restricting amendment or statement does not have causality with the granting of the patent right or maintaining the patent right. Case 2 also involves the effect of “foreseeability” on the application of the doctrine of estoppel, which is not elaborated due to the limited space.
III. Reflection
Originally, the Doctrine of Estoppel restricts the scope of infringement under the Doctrine of Equivalents in infringement litigation. Is it applicable in post grant reviews? The answer is yes. In the Provisions of the Supreme People’s Court on Several Issues Concerning the Application of Law in the Trial of Administrative Cases Involving Patent Grant and Post Grant Ienacted in 2020, Article 3 provides that: “In defining the term of a claim in an administrative case involving patent confirmation, the people’s court may refer to the relevant statement of the patentee that has been adopted by an effective ruling of a civil case involving patent infringement.” By this article, it is intended to guide and urge the patentee to make prudent and credible statements of the meaning of the expression used in the claims in either post grant procedure and infringement litigation, and to prevent the patentee from making contradictory statements in different procedures. By this article, the statements of the patentee in infringement litigation will have a certain adverse effect, preventing the patentee from gaining at both ends.
[ii]
As shown above, Infringement Interpretation Iimposes a restriction onto the statements or amendments of the patentee or applicant. Although Infringement Interpretation IIto some extent restricted the application of the Doctrine of Estoppel, the applicant or patentee should still consider this doctrine and carefully state the opinions of restriction or partial abandonment of the scope of protection of the claims, either in patent grant procedure or in post grant procedure. Furthermore, the allegedly infringing party in an infringement dispute could have a chance to win by applying the Doctrine of Estoppel in view of the prosecution history, the effective invalidation decision or related civil judgment, oral hearing records, and telephone interview records, and so on, associated with the involved patent.
