I. Introduction

Defining the scope of protection for patent rights is a core issue throughout the stages of patent granting, invalidation, and infringement litigation. Due to the complexity of technical solutions and the limitations of language of the claims, there may potentially be certain terms that are vague or ambiguous in the claims. Therefore, claim interpretation may need to rely on further evidence, including intrinsic evidence such as the specification and the prosecution history of the patent and extrinsic evidence such as common knowledge evidence. Accordingly, how to balance the priority of various types of evidence to conduct a comprehensive and objective claim interpretation remains a focal point of controversy in practice.

The "2025 Top Ten Typical Patent Reexamination and Invalidation Cases" recently released by the China National Intellectual Property Administration, along with a number of recent precedents from the Supreme People's Court, provide significant guidance for determining the scope of patent protection. Drawing on several recent relevant cases, this article illustrates the specific paths for claim interpretation from the perspectives of intrinsic and extrinsic evidence to provide a reference for patent practice.

II. Relevant Laws and Regulations

The following are relevant provisions regarding claim interpretation in Chinese laws and regulations:

Patent Law Article 64, Paragraph 1: "The extent of protection of the patent right for invention or utility model shall be determined by the terms of the claims. The description and the appended drawings may be used to interpret the claims."

Patent Examination Guidelines Part II, Chapter 2, Section 3.2.2: "The scope of protection of a claim shall be construed according to the meaning of the words used in the claim. Generally, the words used in a claim shall be understood as having the meaning that they normally have in the relevant art. In particular cases, where the description explicitly gives a certain word a special meaning and, by virtue of the definition of the word in the description, the scope of protection of the claim using the word is defined sufficiently clearly, such a case is also allowed. However, in this case, the examiner should also invite the applicant to amend as far as possible the claim whereby the meaning is clear from the wording of the claim alone."

Interpretation of the Supreme People’ s Court on Several Issues Concerning the Application of Law in the Trial of Patent Infringement Disputes

Article 2: "The People's Court shall determine the content of the claims... based on the record of the claims, combined with the understanding of the claims by a person ordinarily skilled in the art after reading the description and drawings." 

Article 3: "The People's Court may interpret claims using the description and drawings, relevant claims in the claim set, and the patent prosecution history. Where the description has a special definition for a term, that definition shall prevail. If the meaning remains unclear... it may be interpreted in combination with technical dictionaries, textbooks, and other public documents, as well as the common understanding of those skilled in the art."

In view of the above, while the purpose and task of different procedures are different, the general principles established by the above law and regulations are that claim interpretation should be conducted from the perspective of a "person ordinarily skilled in the art (PHOSITA)" and follow the rule of "intrinsic evidence first, supplemented by extrinsic evidence.

III. Case Analysis

The following three cases demonstrate the application of these principles in practice.

Case 1: Patent Invalidation Case - Interpreting Claim Terms with Common Meanings in the Art

Case Background: This case stems from the CNIPA's "2025 Top Ten Typical Patent Reexamination and Invalidation Cases" (Invalidation Decision No. 565224). The involved patent (ZL201611014962.8) relates to an "Offset decoding device, offset coding device, Image filtering device" and is a Standard Essential Patent (SEP) in the field of video coding. During the invalidation procedure, the petitioner alleged that the term "offset" in the claims essentially means a broad "compensation," and submitted the New Oxford English-Chinese Dictionary as extrinsic evidence to prove that the claim features related to "offset" should be identical to "residual compensation" in the prior art, thereby challenging the patent's novelty and inventive step.

Case Analysis: In the Invalidation Decision, the Panel explicitly stated that claim interpretation should be based on the cognition of a PHOSITA. Regarding "offset," the Panel held that while "offset" can be interpreted as "compensation" in general, the intrinsic evidence(including claims, description, and drawings) clearly defines "offset" as a specific technical processing step unique to an offset filter. Furthermore, by referring to the relevant standards associated with this SEP, it was confirmed that a PHOSITA would understand the term "offset" to have a specific technical meaning in the video coding field, rather than a broad dictionary meaning of "compensation." 

Thus, the claims were found to be essentially different from the prior art, possessing novelty and inventiveness.It can be seen that through this case, CNIPA establishes a guiding examination path for the interpretation of the claim in the patent invalidation procedure. Firstly, the technical meaning of terms is determined from the overall technical solution defined by the claims, including the correlation and context of claim features, and secondly, combined with the technical essence and invention purpose disclosed in the specification and drawings, the meaning of the terms is further determined through a comprehensive understanding of the technical solution. In addition, for SEPs, the ordinary meaning of a specific technical term in the field may be determined by the description of the term in the relevant standards, so as to comprehensively interpret the term from the perspective of a PHOSITA.

Case 2: Patent Infringement Case - Priority of Intrinsic Evidence over Extrinsic Evidence

Case Background: This case (Judgement No.: 2021 Supreme Court Min Shen No. 3110) stems from the “Annual Report on Intellectual Property Cases in the Supreme People's Court (2022)” . The involved patent (ZL02135704.8) relates to an "Elastic Force-Couple Barring Apparatus."

The dispute centered on the interpretation of "casing with a U-shaped cross section" and "elastic support." The Plaintiff (i.e., Retrial applicant) submitted extrinsic evidence, such as National Standards for Technical Drawing and Mechanical Properties of Materials, to assert that the "U-shaped" does not require a continuous U-shape and that all rigid materials (e.g., U-steel) have "elasticity" under certain conditions, attempting to expand the scope of protection.

Case Analysis: The Supreme People’ s Court held that: "when interpreting claims, intrinsic evidence such as specification and drawings, patent examination files, etc., has priority over extrinsic evidence such as reference books and textbooks. If the content of the claims can be clearly explained based on intrinsic evidence, it will not be explained based on extrinsic evidence." This case reiterates the core position of intrinsic evidence in the interpretation of claims.

Specifics of the features in dispute in this case are as follows:

1. "U-shaped casing": The specification of the involved patent defines the casing as an oil tank containing lubricating oil. Also, combined with the drawings, a PHOSITA would conclude that the cross-section of the casing must be a continuous, uninterrupted U-shape to realize the function of containing lubricating oil.

2. "Elastic support": Based on the specification, the technical problem to be solved by the patent is caused by the rigid connection of the frame, and it uses the elastic support instead of the rigid support used in the prior art, which solves the technical problem.Therefore, in this specific technical context of the involved patent, the technical solution clearly distinguishes "elasticity" from "rigidity" in the prior art, which cannot be interpreted as the theoretical "elasticity" inherent in rigid materials.

The plaintiff divorced from the intrinsic evidence and explained the claim with extrinsic evidence, such as standards and textbooks, which is contrary to the invention purpose revealed in the specification and drawings, and therefore was not accepted by the court. In judicial practice, the interpretation of claims needs to start with intrinsic evidence and objectively determine the meaning of the terms in the claimed solution. Only when the intrinsic evidence is not clear enough to define the meaning of the term can extrinsic evidence be introduced as an auxiliary explanation. In other words, extrinsic evidence cannot be used as a tool to improperly expand the scope of protection when intrinsic evidence has already provided clear logical guidance or technical distinctions.

Case 3: Patent Infringement Case - Assessing Extrinsic Evidence Based on Technical Proximity

Case Background: This case (Judgement No.: 2020 Supreme Court Zhi Min Zhong No. 580) stems from the "Annual Report on Intellectual Property Cases in the Supreme People's Court (2021)." The involved patent (ZL201010235151.7) relates to a "touch screen and multi channel sampling method thereof." The dispute was whether a "touch screen" must have a physical screen structure. The first-instance court used the Contemporary Chinese Dictionary and the Baidu Baike to rule that a "screen" must be a tangible entity. On appeal, the plaintiff submitted several textbooks in related technical fields as common knowledge evidence to prove that a "touch screen" in this field can include non-contact screens without a physical screen structure.

Case Analysis: The Supreme People’ s Court consulted professional books like Practical Maintenance Technology for Multimedia Computers in this specific field and found that a "touch screen" in the field includes both contact and non-contact (e.g., infrared) types, and ruled that the first-instance court's reliance on general dictionaries not in the specific field was divorced from the technical background. In the final, the Supreme Court supported the plaintiff's interpretation of the claim.

The Court pointed out that if the specification of the patent does not provide a special definition for a technical term in the claims, the term should be interpreted according to the common understanding of a PHOSITA, rather than resorting to its common meaning in daily life. Relevant common knowledge evidence should be assessed based on its proximity to the technical field of the involved patent. In this case, as the patent specification does not provide a specific explanation that differs from the ordinary meaning regarding whether a touch screen must include a physical screen structure, both parties submitted extrinsic evidence favorable to their respective positions. In applying these evidential materials, the Supreme Court took the technical field of the evidence as an evaluation basis, and prioritized common-knowledge evidence in closely related fields to interpret the claim terms, thereby ensuring the interpretation remained consistent with the technical background and knowledge system of the art.

IV. Conclusion

Combining the law, regulations, and judicial practice, the core rules of claim interpretation can be summarized as follows:

1. Comprehensive Assessment from the Perspective of a PHOSITA: Interpretation of claims is, in nature, based on the cognitive ability and status of a PHOSITA, in the technical context of this field, and combined with intrinsic and extrinsic evidence. Therefore, the evidence should be placed in the technical context of the field involved in the patent, and the objective meaning of the term should be determined after the overall analysis of the technical solution.

2. Intrinsic Evidence as the Core: Intrinsic evidence (e.g., specification, drawings, and prosecution history) holds a core position. When intrinsic evidence provides a clear and definite explanation, it generally cannot be overturned by extrinsic evidence.

3. Proximity Principle for Extrinsic Evidence: When introducing extrinsic evidence, its proximity to the technical field of the patent involved should be fully considered. Priority should be given to common-knowledge evidence such as professional textbooks and technical manuals in the related field, rather than general language dictionaries, so as to avoid improper narrowing or expansion of the claim terms out of the context involved in the patent. In particular, for SEPs, relevant standards can be referenced to interpret the terms defined in the claims.