*AI-generated translation, for reference only.

[Keywords] Civil, ownership and infringement of intellectual property rights, confirmation of whether it falls within the protection scope of a patent right, drug patent linkage, equivalents, amendment of claims, dedication, estoppel

Case Fact

The plaintiff, Mo [REDACTED] Company, alleged: Mo [REDACTED] Company is the patentee of the invention patent with patent number 20068004****.7, titled "Pharmaceutical Composition of a Combination of a Dipeptidyl Peptidase-4 Inhibitor and Metformin" (hereinafter referred to as "the patent in question"). The marketing authorization holder of the original drug in question, Sitagliptin Metformin Tablets (II), has registered the patent information in question on the China Listed Drug Patent Information Registration Platform. Qi [REDACTED] Company, using the original drug in question as the reference formulation, completed bioequivalence studies and submitted a generic drug marketing authorization application to the National Medical Products Administration with a Type 4.2 declaration. The technical solution of the generic drug in question falls within the protection scope of claims 4 and 11 of the patent in question. Therefore, it requests a confirmation that the generic drug in question falls within the protection scope of claims 4 and 11 of the patent in question.

The defendant, Qi [REDACTED] Company, argued in its defense: The technical solution of the generic drug in question does not fall within the protection scope of claims 4 and 11 of the patent in question, and requests that the claims of Mo [REDACTED] Company be dismissed.

The court ascertained through trial: During the substantive examination of the patent in question, Mo [REDACTED] Company amended the claims in response to the second Office Action by adding the technical feature "0.5% by weight of a surfactant" and stated in the remarks that "the technical problem to be solved by this application is that the formulation should be bioequivalent to sitagliptin and metformin when administered separately. The addition of 0.5% by weight of a surfactant to the formulation is particularly useful for solving the above technical problem." The only technical feature distinguishing the technical solution of the generic drug in question from claim 4 of the patent in question is that the weight percentage of the surfactant differs from the "0.5% by weight of a surfactant" defined in claim 4.

The Beijing Intellectual Property Court rendered the civil judgment (2022) Jing 73 Min Chu No. 409 on November 21, 2022: dismissing the claims of Mo [REDACTED] Company. After the judgment was pronounced, Mo [REDACTED] Company appealed. The Supreme People's Court rendered the civil judgment (2023) SPC IP Civil Final No. 48 on March 22, 2023: dismissing the appeal and upholding the original judgment.

Judge's Opinion

Both the doctrine of estoppel and the principle of dedication can serve as limitations on the application of the doctrine of equivalents, with the purpose of achieving a reasonable balance between fairly protecting the interests of the patentee and safeguarding the interests of the public. Where the conditions for limiting the application of the doctrine of equivalents are satisfied, it is generally unnecessary to further determine whether the two features are substantially the same in means, function, and effect and whether a person skilled in the art would have been able to conceive of them without the exercise of inventive effort.

In this case, since Qi [REDACTED] Company argued for the application of the doctrine of estoppel based on Mo [REDACTED] Company's amendment of the claims, and for the application of the principle of dedication based on the patent text resulting from the amendment, the court first made a determination on whether the doctrine of estoppel should apply in this case based on the patentee's amendment of the claims.

First, during the substantive examination of the patent in question, to overcome the substantive defects of lack of inventive step and lack of support by the specification, Mo [REDACTED] Company amended the claims twice. The limitation regarding the surfactant in the claims changed from absence to presence and was finally determined to a specific point value by weight. Considering that during substantive examination, there are no restrictions on the manner of amendment of claims, and the numerical ranges described in the specification could all be used as specific limitations for the surfactant in the claims. However, Mo [REDACTED] Company specifically selected the point value "0.5% by weight." It had no evidence or reasonable explanation that the amendment was subject to limitations of expression, that the relinquishment was unforeseeable, or that it was not closely related to the equivalent feature in dispute, or other circumstances based on which it could be determined that the corresponding technical solutions were not relinquished. Therefore, based on the amendment, it can be presumed that Mo [REDACTED] Company has relinquished the scope of protection beyond that point value.

Second, in responding to the second Office Action, Mo [REDACTED] Company, through its remarks, emphasized the special technical effect of adopting the technical solution of 0.5% by weight of surfactant in solving the technical problem to be solved by the patent in question. In other words, during the patent examination procedure, by emphasizing the special technical effect of the preferred technical solution defined by the point value, Mo [REDACTED] Company tailored the scope of protection of the amended claims to the contribution made by the invention as asserted in the specification, thereby overcoming the substantive defects pointed out in the Office Action and obtaining the grant. It has, through the act of making remarks during the examination procedure, made an express indication, clearly and definitively limiting and describing the scope of protection of the amended claims. In determining whether it falls within the protection scope of the patent right, values outside the preferred technical solution limited by that point value should not be included within the scope of protection of the patent right.

Third, Mo [REDACTED] Company argued that the point value of 0.5% was already recorded in original claim 9, and the manner of amendment of the patent in question was to add the technical feature of claim 9 to original independent claim 1, and that it did not explicitly relinquish equivalent features of that technical feature in claim 9. However, for claim 4 asserted by Mo [REDACTED] Company in this case, adding the technical feature of claim 9 to original independent claim 1 precisely narrowed the scope of protection of claim 4, enabling claim 4, which depends on claim 1, to overcome the defect of lack of support by the specification. As for the manner of amendment itself, it does not affect the application of the doctrine of estoppel.

In summary, the doctrine of estoppel should apply in this case. The technical feature adopted in the generic drug in question does not constitute an equivalent feature to the technical feature of 0.5% by weight of surfactant in claim 4 of the patent in question. The technical solution of the generic drug in question does not fall within the protection scope of claim 4 of the patent in question, nor does it fall within the protection scope of claim 11 of the patent in question.

Judgment Digest

I. Where the conditions for limiting the application of the doctrine of equivalents, such as estoppel or dedication, are met, the application of the doctrine of equivalents may generally be excluded, without the need to further determine whether the two technical features are substantially the same in means, function, and effect and whether a person skilled in the art would have been able to conceive of them without the exercise of inventive effort.

II.Where the patentee has amended the claims, if it claims that a specific technical solution between the scope of protection of the original claims and the amended claims has not been relinquished, it shall adduce evidence or reasonably explain that the timing and manner of the amendment were strictly restricted, that there were limitations in expression, that the relinquishment was unforeseeable, or that it was not closely related to the equivalent feature in dispute, or other circumstances based on which it can be determined that the corresponding technical solution was not relinquished.

Related Index

Article 64, Paragraph 1, Article 76, Paragraph 1 of the Patent Law of the People's Republic of China

First Instance: Civil Judgment (2022) Jing 73 Min Chu No. 409 of the Beijing Intellectual Property Court (December 21, 2022)

Second Instance: Civil Judgment (2023) SPC IP Civil Final No. 48 of the Supreme People's Court (March 22, 2023)

Retrial: Civil Ruling (2023) SPC Min Shen No. 1673 of the Supreme People's Court (December 27, 2023)

The text of this case was adjusted as of June 12, 2025.