Patent Inventiveness in China: Why “Common Knowledge” Must Be Proven, Not Assumed

A Case Study of the "Electronic Blackboard" Case, (2025) SPC Zhi Xing Zhong No. 286

I. Introduction

In assessing inventive step for invention patents, determining whether a technical solution would have been “readily conceivable” to a person skilled in the art has long been one of the most disputed and uncertain aspects of the analysis. In practice, Examiners far too often have a flawed tendency to deem a technical means a "conventional choice" in the art simply because the prior art discloses a similar function or means. This leads to Examiners directly concluding that the claim lacks inventive step as a whole. This approach suffers from two major defects:

• It lacks a holistic evaluation of the distinguishing technical features.

• The determination of "common knowledge" or "conventional means" is made without evidentiary support.

This easily leads to hindsight bias.

In this recent 2025 case, SPC Zhi Xing Zhong No. 286 (the "Electronic Blackboard" case), the Supreme People's Court (SPC) systematically addressed these issues, further clarifying the legal standards for determining obviousness.

II. Case Overview and Background

Petitioner Chen Moufeng (陈某风) filed an invalidation request against a patent covering electronic blackboards¹ held by patentee Guangzhou Langmou Electronic Technology Co., Ltd. (广州朗某电子科技股份有限公司).

The pivotal issue related to inventive step: whether the prior art disclosed all distinguishing technical features as a whole, and whether those features were truly obvious.

The core distinguishing technical solution of Claim 1 consists of a four-step sequence:

• Acquiring a User ID and a Course Tag;
• matching the User ID to retrieve the user's frequently used handwriting color;
• retrieving a sequence of use durations for all colors used in that specific course, and selecting the top-ranked colors as "filtered and optimized" colors;
• combining these colors into a handwriting color invocation group placed within an electronic chalkbox.

The invalidation petitioner argued that the prior art disclosed color selection, and that relying on user preferences or group statistics constituted conventional means, rendering the solution obvious.

The CNIPA and the Court of First Instance agreed with the petitioner, invalidating the patent.

However, the SPC reversed this decision on appeal, revoking the invalidation decision.

Table 1: Feature-by-Feature Comparison of Judicial Views

Table 2: Comparison of Adjudication Logic across Trial Stages

III. What is the Standard for Inventive Step? The SPC’s Position

To correctly assess whether an invention is obvious, courts must accurately identify the distinguishing technical features over the closest prior art, ascertain the technical problem actually solved, and determine whether the prior art provides a technical suggestion (teaching).

But how does one determine whether something is a technical suggestion?

The SPC Standard: A technical suggestion exists only if the prior art motivates a person skilled in the art to apply the distinguishing features to the closest prior art in order to solve the targeted technical problem. If a feature consists of limited, universally applied options in the industry, it may be deemed a conventional choice. However, "common knowledge" cannot be asserted arbitrarily; it must be proven via evidence or supported by robust, sufficient legal reasoning.

Applying this to the present case:

Distinction from D1: The color groups in D1 are populated manually by the user based on immediate preference, lacking any correlation with course tags or presentation content. Furthermore, D1's UI requires navigating a "writing menu" before selecting colors, which contradicts Claim 1's automated requirement of "forming a group and placing it into the electronic chalkbox." The lower instances erred by ignoring this structural difference.

Distinction from D4: The group statistics in D4 focus on demographic traits (age, gender, location) to infer broad user preferences for displaying options or setting a default color. D4 fails to track group usage habits tied to a specific processing object (such as a digital photo, video, or course content) to calculate duration-based preferences. Thus, D4's disclosure does not teach the generation of a "filtered and optimized handwriting color" based on a course tag sequence.

Conclusion: Except for the preamble, the SPC concluded that the entirety of Claim 1 constituted distinguishing features. Therefore, because the "course tag" feature and the automated duration-filtering logic were neither disclosed by D4 nor proven to be common knowledge, the SPC concluded that the obviousness determination was legally groundless and proceeded to reverse the decision.

IV. Recommendations for Patent Practitioners

This judgment clarifies that it is improper to dissect an integrated technical solution into isolated components, label each as a "conventional choice" in a vacuum, and conclude a lack of inventive step without explicit prior art teachings.

The SPC takes a strong stance that when the “characterizing portion” of a claim (i.e., the distinguishing technical features) forms an integrated distinguishing feature, and no prior art or common knowledge evidence refutes it as a whole, the claim possesses inventive step.

• When faced with rejections involving inventive step, applicants can consider the following: "Enforce” a Strict Burden of Proof for Common Knowledge: Formally object to assertions of "conventional means" or "common knowledge" that rely on mere intuition or subjective Examiner experience. Require Examiners (or petitioners) to provide concrete evidence or rigorous, technical deductions showing that the alleged “obvious” feature(s) represent a strictly limited option universally applied in the field.
  
• When Combining Features: ”As a Whole” is the Standard: Actively counter Examiners’ attempts to divide a claim into isolated features when trying to attack inventive step. As shown in this case, isolating the final integration step ("placing the group into the chalkbox") from the data-filtering steps made it easier for the Examiner to show that certain isolated features were already disclosed in the prior art.
  
• Ensure the Technical Problem is Precisely Defined Towards the Technical Features of the Technical Solution. At the drafting stage, draft the specification to clearly express the specific technical problem. At the prosecution stage, push back if the Examiner defines the wrong technical problem. In this case, if the "Course Tag" had been removed, the technical problem would have been broadened into a generic "color selection" problem, leading to an incorrect conclusion of lack of inventive step.

Ultimately, Case No. 286 clarifies the SPC’s strong position that obviousness cannot be dictated by hindsight bias. When evaluating inventive step, practitioners and Examiners alike should closely scrutinize the exact data processing flows, specific application contexts, and actual technical effects of the features at issue. If the prior art lacks a holistic teaching to combine these elements to solve the specific technical problem, an assertion of obviousness cannot stand.

This case, together with other recent cases, is great news for innovators and patentees. The SPC is clearly trying to eliminate vague rejections that are grounded in hindsight bias by increasing the evidentiary requirements needed to establish a proper inventive step challenge.

Source: Intellectual Property Court of the Supreme People's Court, Abstract of Adjudication Rules

This article is for general informational purposes only and should not be considered legal advice or a legal opinion on a specific set of facts.

1. CN113253961B An Electronic Blackboard Control Method, System, Electronic Blackboard, and Readable Medium (一种电子黑板控制方法、系统、电子黑板和可读介质). ↩︎