Markush claims in China - what can be arbitrarily deleted during invalidation?
Since 2010, the China Patent Re-examination Board (PRB) has published the top 10 patent invalidation cases of the year in April of each year. The selection criteria are high social concern, significant impact on the related industry, or involve difficult legal issues and important examination criteria. Below is one of the top 10 cases that discusses post filing data in China patents.
This case (Beijing Winsunny Harmony Science & Technology Co., Ltd. v. Daiichi Sankyo Co., Ltd) describes an invalidation request of Daiichi Sankyo’s Chinese invention patent 97126347.7 related to processes of preparing pharmaceutical compositions for treating or preventing hypertension. The patent covered the marketed hypertension drug Olmesartan medoxomil.
During the invalidation, the patentee made select amendments to multiple Markush groups, deleting particular individual components from several different R groups of a molecule. The issue at hand is whether these amendments are allowable during an invalidation proceeding, which typically has very strict rules regarding amendments.
Courts Differ on Markush Claims in China
In short, it boils down to how the courts interpret a Markush claim. Does it refers to a general technical solution or parallel embodiments of several technical solutions? If it is one general solution, should you really be able to pick and carve away at its scope? Does doing so create a new scope that has a different technical effect than the original invention? If so, is that allowable?
The Patent Re-examination Board (PRB) and the Beijing High People’s Court (BHPC) disagreed on how to interpret Markush claims in China. The PRB felt that arbitrary amendments should not be allowed because a Markush claim is directed towards a general technical solution. Arbitrarily deleting elements during invalidation would thus create new scopes of protection that could have different technical solutions.
The BHPC thought that Markush groups represented alternate parallel technical solutions, and thus deleting one or more options just narrowed the scope of the claim. The Supreme People’s Court (SPC) ruled that the amendments were allowable. Additionally, the SPC indicated that such types of amendments may be allowed during invalidation as long as the amendments did not generate a scope that possessed a new function or technical effect.
Markush Claims in China Drafting Tips
Applicants should be aware that amendments which carve out a new scope with improved technical effect (as compared to the original scope) may not be allowable. During an invalidation proceeding, it will be difficult to amend claims to a narrower scope with improved technical results to overcome inventive step. Instead, at the time of drafting, applicants should draft several dependent claims directed towards alternate scopes with varying qualities of efficacy, including very narrow claims covering the best, most efficacious compounds. It is risky to rely on being able to carve out scope from broader claims during an invalidation challenge.
A side note on inventive step . . .
Interestingly, this case also briefly discussed inventive step. The petitioners argued that the patent lacked inventive step because a specific embodiment in the patent had equivalent technical effect as a prior art compound. The PRB disagreed and emphasized that inventiveness is actually a three-step determination, and it is inappropriate to directly apply just the “unexpected technical effect” test to see if claims are inventive or not.
Sources: Lexology, Sanyou IP Group
A Stratification Too Far? How the CNIPA Draws the Line on Patient Subgroups in a Recent Precision Medicine Invalidation Case
2026年2月27日
Precision medicine is rapidly transforming the global healthcare landscape, providing more effective therapies and better patient outcomes through targeted solutions. As therapeutics move away from the traditional “one-size-fits-all” model, unique challenges are presented in the patent examination process. The 2024 Top 10 Patent Re-examination and Invalidation case highlighted below provides further insight into how the […]
閱讀更多 >
How to Protect a Crystal Form (Polymorph) Patent in China
2025年6月4日
Crystalline forms are critical to pharmaceutical patents, offering extended protection for improved stability, bioavailability, or manufacturability. However, securing such patents in China has grown increasingly difficult due to the China National Intellectual Property Administration (CNIPA)’s strict patentability criteria. Unlike the U.S. or Europe, where structural novelty or problem-solving utility may suffice, China demands quantifiable evidence of […]
閱讀更多 >
CNIPA Releases Interim Measures for the Amended Chinese Patent Law Going Into Effect June 1, 2021
2021年5月28日
Breaking News! We finally have more details about the new Chinese Patent Law which will go into effect on June 1, 2021. The full set of measure can be found at this link. Below are some pertinent points. No Implementation Rules . . . . Yet The new Implementation Rules will not be available by […]
閱讀更多 >
New Remedy in China for Fixing "Errors" in a Patent Application: Incorporation by Reference
2024年3月21日
Background As mentioned in our earlier article, the Implementation Regulations of the Chinese Patent Law (“Regulations”, similar to the CFR in the US) were approved in November, and the CNIPA finally made public the full text of the Regulations just before the arrival of the New Year. At the same time, the CNIPA also released the new […]
閱讀更多 >
我們過去活動
Pauli Wong as a Guest speaker for “Entrepreneurial Workshop” in Poly U
2026年6月16日
Eagle IP Recognized as Top Tier Firm (Tier 1) for Patent Prosecution in IP Stars 2026 Patent Firms Ranking List
2026年6月5日
Eagle IP Achieves Top Ranking in 2026 IAM Patent 1000
2026年6月2日
Eagle IP to Participate in AIPLA 2026 Spring Meeting in San Francisco
2026年5月8日
Eagle IP has been named as the Winner of the LSPN Cross-Border Collaboration Partner of the Year Award at the LSPN Awards USA 2026
2026年5月8日
Eagle IP to Attend INTA 2026 Annual Meeting in London
