Assessing a Prior-Art Defence in China: Test the Disclosure Date and Technical Match

By Pan Jianxing · Published 26 October 2026

A foreign patent owner receives an old catalogue in response to an infringement allegation in China. The supplier says the disputed product was already public. That response deserves a structured review: an authentic old document may show too little, while a detailed technical drawing may have remained confidential.

Under Article 67 of the Patent Law as amended in 2020, evidence establishing that the accused technology or design belongs to the prior art or prior design can defeat an infringement claim. Rights holders should assess this issue before committing to demands that assume every similarity supports liability.

Fix the relevant patent and date

Start with the Chinese patent, its application and priority records, the rights asserted and the accused product version. Articles 22 and 23 define prior art and prior design by reference to what was publicly known in China or abroad before the application date. Article 12 of the 2023 Implementing Regulations generally treats that reference as the priority date where priority exists, subject to the stated statutory exceptions.

Do not simply copy the earliest date printed on a patent cover. Check whether the priority relied on applies to the relevant subject matter. For an older patent, Article 22 of the SPC Patent Infringement Interpretation II, as amended in 2020, requires the definition of prior art or prior design to follow the Patent Law in force at the application date. Record that temporal analysis explicitly.

Prove public availability, not just document age

Separate the date a document was created from the date its contents became available to the public. Useful material may include published patent documents, distributed catalogues, publicly accessible product manuals, exhibition records and evidence of earlier sales. Preserve the complete source and the facts showing disclosure.

A catalogue bearing a year on its cover does not alone explain when it circulated. Seek distribution records, dated correspondence, library records or independent recipients where available. For an online page, retain its address, complete content and evidence of the earlier version. A present-day capture proves what is visible now; it does not automatically establish the same content existed before the relevant date.

Confidential supplier drawings require a different assessment. An early file timestamp may help establish development history, but a document shared under confidentiality obligations is not necessarily public prior art. Record access restrictions and recipients instead of silently treating all earlier material as publicly disclosed.

Compare the accused implementation with the earlier disclosure

Article 14 of the SPC Patent Infringement Interpretation compares all accused technical features alleged to fall within the patent’s scope with corresponding features in one prior technical solution. The rule asks whether they are identical or have no substantive difference. For designs, it compares the accused design with one prior design on the stated standard.

Prepare a comparison showing the accused feature, its evidence and the exact passage or drawing in the earlier disclosure. Identify missing detail and disputed inferences. This is not a simple comparison of the earlier publication with the patent claim, and a collection of unrelated documents should not be presented as if it were one disclosed solution.

Several records may help prove the date, authenticity or content of the same earlier product. Explain their relationship. Keep that evidential function distinct from assembling separate technical features from different products to create a hypothetical earlier solution.

Keep the defence separate from invalidation

A prior-art defence concerns the accused implementation in an infringement dispute. A request under Article 45 to invalidate the patent follows a separate procedure before the patent administration authority. The two assessments may use overlapping evidence, but one filing or argument is not proof that the other procedure has succeeded.

Keep separate records of the court’s directions, any invalidation request and its actual procedural status. Do not assume that an invalidation filing automatically cancels the patent or suspends the infringement proceedings. Obtain advice on the particular procedural position and meet existing evidence deadlines while it is being assessed.

Build a useful response file

For the hypothetical catalogue dispute, a practical file contains the full catalogue, disclosure evidence, the relevant patent records, a preserved accused sample and a feature comparison. Record the source and custodian of each item. Retain originals and make translations and annotations as separate, traceable working copies.

The rights holder can then distinguish an unsupported assertion from a material defence, identify what additional evidence is needed and reconsider the scope of the allegation where appropriate. Contact Pan Jianxing with the Chinese patent number, the disputed product and a non-confidential description of the earlier material for an assessment of the next steps.

Pan Jianxing
China-qualified lawyer · Partner, 北京市长安律师事务所
Beijing & Shenzhen
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