Responding to inventive-step objections based on common general knowledge

1. The issue

Part II, Chapter 4 of the Guidelines for Patent Examination provides that inventive step may be assessed by combining different technical teachings disclosed in one or more prior-art documents. Under this principle, examiners often combine at least one reference with common general knowledge to assess the claimed invention.

Disputes often focus on whether one or more technical features constitute common general knowledge. An applicant may argue that the examiner has provided no evidence that the feature in question belongs to such knowledge and expect this argument to overcome the objection. This approach is often unsuccessful. Because the relevant laws and regulations do not expressly assign the burden of proof to the examiner in this situation, responding to an inventive-step objection based on common general knowledge can be difficult.

2. Analysis

The Chinese Guidelines for Patent Examination describe common general knowledge as including a customary means in the art for solving the technical problem reformulated in light of the closest prior art, or a technical means disclosed in a textbook or reference book. The important elements are therefore the technical problem to be solved and whether the technical feature is a customary means or is recorded in such a publication.

When an examiner relies on common general knowledge to assess inventive step, the applicant may consider the following approaches.

2.1 Identify the actual common general knowledge

The applicant can identify the specific technical means that constitute common general knowledge in the relevant field and explain how they differ from the feature in question. Rather than merely denying that the feature is common general knowledge, the applicant can find and present what actually constitutes that knowledge.

Specifically, the applicant can consult authoritative textbooks or reference books in the field, identify the means they describe for solving the reformulated technical problem, and explain why those means constitute common general knowledge. The applicant can then compare those means with the feature in the claims, carefully analysing the differences in technical implementation and the technical effects of the claimed feature relative to those means. This can demonstrate that the feature differs from common general knowledge in the field.

The argument may be more persuasive if the cited references or other publications in the field contain passages showing that, under ordinary circumstances, the feature in question would not be used to solve that technical problem.

2.2 Rely on the technical effect

The applicant can also rely on the feature’s technical effect to show that it is not common general knowledge. Technical effects provide important evidence of inventive step under Chinese patent law. An unexpected technical effect can support the inventiveness of a technical solution.

Based on the description, the applicant can explain that a person skilled in the art would not readily conceive of the feature’s role in solving the reformulated technical problem and could not foresee the technical effect directly produced by that feature.

In other words, before reading the application, a skilled person might know that the feature produces other technical effects, but would not think of using it to solve the reformulated problem and obtain the effect described in the application. The performance or advantages produced by the feature would then exceed the skilled person’s expectations. A feature used in this way would not be common general knowledge for solving that problem.

If the description does not expressly state the technical effect corresponding to the feature, the applicant may consider a hypothetical removal of that feature from the claimed solution. If the remaining features cannot form a complete technical solution or solve the reformulated problem, this demonstrates the feature’s substantial contribution to the claimed combination.

The applicant can further argue that only after reading the application would a skilled person understand that the feature produces the relevant technical effect. This can support the argument that the effect is not an ordinary one in the field. A feature that makes a substantial contribution and produces such an effect can therefore be distinguished from common general knowledge.

2.3 Analyse interactions between technical features

The applicant can analyse how the feature in question interacts with the other technical features. Features in an independent or dependent claim are not isolated elements; together, they form a whole in which the elements interact and influence one another. A feature considered alone may appear to be a conventional choice. However, if its interaction with other features solves a technical problem and produces an effect different from its effect in isolation, the combined use may fall outside the definition of common general knowledge.

For example, in Chinese patent application No. 03121391.X, the independent claim concerns an optical/electrical multiplexing method supporting a multi-gigabit Ethernet terminal. The method includes the following steps:

(a) Using a physical-layer application-specific integrated circuit with line-diagnostic and port-multiplexing functions, provide each user link with a user port corresponding to a gigabit electrical interface and a user port corresponding to a gigabit optical interface.

(b) Determine the active user port according to real-time detection signals indicating the link status of the two ports; configure the identified active port as the enabled port; and use that enabled port to transmit the user link’s data.

The examiner cited two references and concluded that the feature not disclosed in them—configuring the identified active user port as the enabled port—was common general knowledge in the field.

The applicant considered that, although the feature’s contribution might not be obvious when viewed alone, it played a fundamental role in the overall solution and was not common general knowledge. The response therefore analysed the interaction between that feature and the other claimed features.

The direct effect of configuring the identified active port as the enabled port is to ensure that the enabled port can transmit data. When combined with the other features of claim 1, however, the enabled electrical or optical interface transmits user data according to the link status of the different ports. The Ethernet port can thereby support both electrical and optical interfaces without replacing the interface module. Switching between the optical and electrical interfaces requires changing the enabled interface without interrupting the user link.

In the claimed combination, the feature thus helps achieve the effects of supporting both interface types and avoiding interruption of the user link during optical/electrical switching. These effects cannot be obtained directly from the feature in isolation. The applicant therefore argued that configuring the active user port as the enabled port was not common general knowledge in the context of the claimed solution. The examiner accepted this response.

3. Conclusion

When an examiner treats a distinguishing feature as common general knowledge in assessing inventive step, the applicant’s response will inevitably address that feature’s functions and technical effects. When preparing an application, it is therefore useful to describe in detail the role of each feature in the overall solution, as well as the effects achieved by individual features and their combinations. This provides a stronger basis for responding to later office actions.