I. Introduction

The China National Intellectual Property Administration (CNIPA) released Top 10 Patent Reexamination and Invalidation Cases on April 26, 2025, which included a typical example of applying evidence of public prior use in the invalidation procedure (Invalidation Decision No. 567474). This case provides practical guidance for both petitioners and patentees in the invalidation procedure on how to use such evidence.

II. Challenges in application of public prior use in patent invalidation procedure

Regarding public prior use, the Guidelines for Patent Examination stipulate in Section II, Chapter 3 that: “When the use of a technical solution results in its disclosure, or places it in a state available to the public, such disclosure is referred to as public prior use.” To succeed with public prior use, the petitioners need to prove the date of prior use, what was made available to the public, and its availability to the public.

However, the Guidelines for Patent Examination provide only general stipulations for public prior use, and lack detailed operational guidance. In practice, the application of the evidence of public prior use still faces multiple challenges, such as difficulties in organizing the evidence chain, issues regarding the probative force, and an unclear standard of proof, etc.

A. Difficulties in organizing the evidence chain

Only relying on the above general stipulations related to public prior use, the petitioners may be confused about the legal requirements that the evidence of public prior use shall satisfy. In practice, some examiners deem that the legal requirements of the evidence of public prior use comprise the following four items: (1) whether the alleged technical solution was actually exploited, such as through sale, use, display or the like, that is, the “using act” requirement; (2) whether the technical solution involved by the using act contains substantive information that can support a meaningful comparison with the patent in suit, that is , the “technical solution” requirement; 

(3) whether the substantive information was in a state available to the public, that is, the “public-availability” requirement; (4) whether the state available to the public existed prior to the filing date of the patent in suit, that is, the “disclosure date” requirement.

It can be seen that, since the legal requirements of public prior use are complex, it is difficult for the petitioners to organize the evidence chain. Based on the above requirements, the invalidation petitioners may have to combine multiple pieces of evidence to meet a single legal requirement. That is, the threshold for organizing the evidence chain of public prior is extremely high, and the evidence chain is venerable to the challenges from patentees. 

For example, for the case of Invalidation Decision No. 35297 (CN 201520396790.X), the petitioners provide multiple pieces of evidence to prove the technical solution involved in the patent in suit is disclosed by the public prior display, including (1) videos, to prove that a third party display a product related to the technical solution involved in the patent in suit, (2) an expert opinion report on a portable hard drive that stored the video and testimony of a witness, to prove that this display occurred before the filing date of the patent in suit,(3) sales contracts and invoices, to support the disclosure date proved by the second set of evidence, and other supporting evidence. It is clear that the above evidence is used by the petitioner to prove that the technical solution is disclosed by the act of promotion, the petitioner aims to provide a complete evidence chain to meet each legal requirement of public prior use.

However, the evidence around the “disclosure date” requirement is not accepted by the panel. Specifically, the panel holds that the witness is an employee of the petitioner’ s company, the testimony of whom is not strong enough to prove the disclosure date; the expert opinion report does not record the original source of the said hard drive or the videos, which can not prove the disclosure date either; the sale contracts and the invoices are copies, the authenticity of which is not accepted. Therefore, the above evidence is not deemed as the prior art of the patent in suit.

B. Issues regarding the probative force

In practice, the probative force of the public prior use evidence is always vulnerable to the patentee’ s attack. Usually, a major challenge lies in how to prove that the present condition of a product (as the evidence) matches its state as of the disclosure date without any alteration. That is to say, the technical solution involved in the current product shall be identical to the technical solution involved in the past product when the alleged use took place. In other words, the consistency between the current product and the past product shall be proved. That requires the petitioners to prove a past fact, so the difficulty of proof is relatively high. In practice, there are many cases where the patentee’ s challenges about the consistency of the product are supported. 

For example, for the case of Invalidation Decision No. 34872 (CN 201010167783.4), the patentee argues that since the power strip that the petitioner purchased for notarization was in a condition open to altered by anyone before the notarial sealing, and the power strip is fixed by screws, there is no assurance that the internal structure remained unchanged from the alleged sale date to the sealing date. The panel finally supports the patentee’ s arguments, holds that since the power strip is small and easy to disassemble, and there is no evidence to prove that the internal structure of the power strip had not been altered from the alleged sale date to the sealing date, the existing evidence is insufficient to prove that the internal structure of the above power strip could be prior art of this patent. 

Another example is the case of Invalidation Decision No. 54051 (CN 201780016029.0). In this case the panel holds that since the product submitted for test is not the product purchased and sealed by the petitioners through notarization, there is no relevance between the test result of the test report and the product purchased and sealed by notarization. Therefore, the evidence chain of public prior use is not established.

C. Unclear standard of proof

Due to the challenges in the evidence chain and probative force set forth hereinbefore, the petitioners are unsure whether the evidence of public prior use has met the standard of proof, or even what the standard of proof is, while the patentee likewise has no clear point at which the burden of proof shifts. 

III. Guidance provided by the CNIPA

The typical case of Invalidation Decision No. 567474 involves an invention patent No. 201280016850X, entitled “Hot stamped high strength part excellent in post painting anticorrosion property and method of production of same” . 

In this case, the petitioners used a second-hand vehicle as the key evidence of public prior use, and proved that the second-hand vehicle could serve as the prior art for the patent in suit successfully. Then, it is proved that all the technical features of the patent in suit are disclosed by this evidence through sampling and testing of the vehicle, thus undermining the novelty and inventiveness of the patent in suit. This case provides practical guidance for the evidence of public prior use in the terms of organizing the evidence chain, probative force of evidence, and standard of proof. Specifically:

A. In terms of organizing the evidence chain, the evidence should form a complete legal fact, and the pieces of evidence should corroborate each other without obvious contradictions. In this case, the “high-strength parts” claimed in the patent in suit mainly relate to the plating steel sheet technology for the structural “skeleton” of a vehicle, typically employed in pillars, door impact beams, bumpers, and other similar parts. The petitioners submitted a set of evidence of prior public use concerning a FIAT 500 vehicle, covering the entire chain, from purchase of the vehicle, disassembly of parts, transport of parts, to final laboratory testing, each step of which was fully notarized by the petitioners.

Specifically, regarding the purchase step, the notarized certificate includes the statement associated with the vehicle insurance record made by the seller and the transfer certificate. This set of evidence is used to prove that the vehicle was made publicly available before the priority date of the patent in suit. 

Regarding the disassembly step, the notarized certificate includes the statement of the seller about the insurance status of the vehicle, photographs of the vehicle before and after the disassembly of parts, such as the bumper, anti-collision beam, and B-pillar in the repair shop, and the statement made by the repair shop worker attesting that all parts are original. This set of evidence is used to prove that no part was ever altered.

Regarding the transport step, the notarized certificate includes the photographs showing the parts being sealed, shipped, and received under the witness of the notary. This set of evidence is used to prove that no part was ever altered.

Regarding the testing step, the notarized certificate includes the process of sampling and sending the samples to the testing institution, witnessed by the notary. The resulting test report shows that the test results of the ]anti-collision beam sample disclose all features of claim 1 of the patent in suit.

From the above steps, it can be seen that: (1) the “using act” requirement is met through the sale act; (2) the “disclosure date” requirement is met since the vehicle insurance record and the transfer certificate prove that the disclosure date is prior to the priority date of the patent in suit; (3) the “public-availability” requirement is met  since the fact that the vehicle is sold to the general public proves that the technical solution is available to the public; and (4) the “technical solution” requirement is met since the result of the test report shows the technical solution involved in the vehicle is the same as the technical solution claimed in the patent in suit. Therefore, the petitioners organized the entire evidence chain in order based on all requirements of the public prior use.

B. In terms of the probative force, in order to prove that the product has not been altered, full-process notarization enhances the authenticity of the petitioner’ s collection of evidence; statements and acts performed by disinterested third parties influence the panel’ s inner conviction; emphasizing the difficulties of altering based on characteristics of the product can enhance the probative force.

In this case, the patentee also argued that the statement associated with the vehicle insurance record and the testimony of the repair shop worker have low probative force and are insufficient to prove that the vehicle was not repaired. Besides, the patentee argued that the evidence collection process of purchasing the vehicle and contended that parts could have been altered while the vehicle was being transported to the repair shop.

However, the panel holds that, first, the purchase and disassembly of the vehicle were carried out under the witness of the notary, so it is unlikely that the parts were altered. Second, regarding the probative force of the two statements, as an unrelated third-party enterprise selling the vehicle, there is no evidence to show that the seller would give false proof of the insurance information or even alter the core structural parts of the vehicle; as a professional technician, the repair shop worker can judge whether the core parts have been altered, and his statement would be more cautious under the witness of the notary. Moreover, the insurance record and the testimony of the repair shop worker mutually confirm that the disassembled parts of the vehicle have not been altered. Considering the experience, the disassembled parts in the evidence are non-wearing parts of the vehicle (such as the bumper), and unless the entire chassis of the vehicle had suffered a major collision, there is no need to alter the parts. Even if the parts are altered, it is easy to leave obvious traces. Therefore, the panel holds that the parts are not altered, and the vehicle can be the prior art of this case.

C. In terms of standard of proof, the evidence chain should reach the standard of high probability, and then the burden of proof will shift to the patentee.

After the above-mentioned proof, the panel holds that the petitioners have fulfilled the burden of proof, and the evidence can corroborate each other. The evidence chain has met the standard of high probability, which can prove that the tested parts belong to the original parts of the purchased vehicle. The patentee only challenged the probative force of the certain evidence without submitting the convincing contrary evidence, which is not sufficient to deny the probative force of the entire evidence chain.

That is to say, with respect to the evidence of public prior use, if the evidence chain provided by the petitioners can prove the legal fact, and the patentee fails to provide persuasive counter-arguments and contrary evidence, the evidence of public prior use is deemed to satisfy the standard of proof.

For more understanding of this standard of high probability, reference can be made to Article 108.1 of the Interpretation of the Supreme People’ s Court on the Application of the Civil Procedure Law of the People’ s Republic of China: “Where a party bearing the burden of proof offers evidence, and the People’ s Court, after examining it and taking the relevant facts into account, is convinced that the fact to be proved is highly probable, it shall find that the fact exists.” In other words, as long as the evidence chain shows that the existence of the fact to be proved is highly probable, the petitioner has fulfilled the initial burden of proof; the burden of proof then shifts to the patentee. If the patentee fails to provide persuasive counter-evidence, he must bear the adverse consequences of failing to prove.

IIII. Conclusion

Invalidating a patent relying on the evidence of public prior use is possible and practical. For the petitioners, the evidence should be collected based on every legal requirement of public prior use; moreover, the integrity of the evidence chain should be focused,especially those links most vulnerable to attack on the consistency of the product. Conversely, the patentees can focus on the weak links in the evidence chain, challenging the consistency of the product, the reliability of the disclosure date, the authenticity of the evidence, and any other soft spots. We trust these observations will assist our clients in the CN practice.