By Lily Zhang, Terry Lu

Lexfield Law Offices/联德律师事务所 

A Markush Claim is a claim drafting method commonly used in chemical and pharmaceutical patents. By defining a variety of parallel and alternative groups in the chemical formula, Markush claims can represent a large number of compounds in a generalized manner and become an effective method for inventors to construct multi-level protection scopes based on the chemical structure of the core compound. The legal definition of Markush claims is not provided in the current patent law system of China, which leads to controversy among practitioners in interpretation and amendment of Markush claims. In a recent retrial judgement, Beijing Winsunny Harmony Science & Technology Co., Ltd. v. Daiichi Sankyo Co., Ltd. ( “Daiichi Sankyo case”)[1], the Supreme People’s Court (“SPC”) provided some guidance on the manner of amending Markush claims in invalidation proceedings. This case was recently selected by the Supreme People's Court as “The Top 10 Intellectual Property Cases of Chinese Courts in 2017”.

I. Manner of amending Markush Claims in invalidation proceedings from the guidance of Daiichi Sankyo case

a. Brief Introduction

Daiichi Sankyo Co., Ltd. (“Daiichi Sankyo”) is the patentee of an invention patent No. 97126347.7 entitled “Preparation Method of a Pharmaceutical Composition for the Treatment or Prophylaxis of Hypertension”, which protects a best-selling drug for hypertension, Olmesartan medoxomil. In 2010, Beijing Winsunny Harmony Science & Technology Co., Ltd. (“Beijing Winsunny”) filed an invalidation request before the Patent Reexamination Board (“PRB”) regarding the patent. One of the issues in this case is whether the patentee should be allowed, in the invalidation proceedings, to amend the Markush claims by deleting several alternative groups in the Markush formula. After the first and second instance of administrative litigation, the case was recently heard before the SPC during retrial proceedings, where it reached its final conclusion. The process of the litigation provides perspectives into ways to resolve the issue of amending Markush claims.

b. The PRB and Beijing First Intermediate People’s Court (“BFIPC”): Deleting alternative options in Markush claims is not allowed during invalidation proceedings

The PRB originally held that a Markush claim should be interpreted as a whole generalized technical solution, and since arbitrary deletion of alternative options or groups may develop new protection scopes, the deletion of alternative groups does not belong to the deletion of parallel technical solutions. Accordingly, such types of amendments to Markush claims should not be allowed during invalidation proceedings. The PRB further stated that allowing the deletion of any options or groups in Markush claims will ruin the publicity and certainty of the claims and undermine the public’s reliance interest., it is unconscionable to the public if the patent barrier is too unassailable to be invalidated because the patentee could construct different protection scopes by repeatedly deleting alternative options so as to circumvent the prior art evidence submitted by petitioner.[2] BFIPC defers to PRB and affirms the decision of PRB.[3]

c. Beijing High People’s Court (“BHPC”): Deleting alternative options in Markush claims should be allowed during invalidation proceedings

The BHPC held the complete opposite. BHPC stated that[4] a Markush claim should be interpreted as a set of multiple variations and deletion of alternative options belongs to the deletion of parallel technical solutions and narrows the protection scope of the claim. Such amendments are in line with the patent law without causing harm to the public interest. Therefore, the deletion of alternative groups in Markush claims should be allowed during invalidation proceedings. The BHPC also held that the limitation of amendment of Markush claims in invalidation proceedings merely lies in that the amended claims should not become specific compounds which not recited in the specification.

d. The SPC：The amendment of Markush claims should be strictly limited in invalidation proceedings.

The SPC held in the retrial judgement that, in the value of fairness, the interpretation of Markush claims should be constrained. Markush Claims should be considered generalized combinations, that is, as a set of Markush element, rather than a set of specific compounds. Thus, the amendment of Markush claims should be strictly limited in invalidation proceedings. At the same time, the SPC proposed a standard for allowing amendments of Markush claims in invalidation proceedings: the amendments shall not generate a class of, or a single compound with, a new function or effect, although unique factors specific to a particular case should also be considered.

e. Further Analysis

The Daiichi Sankyo case illustrates that the PRB, BFIPC and BHPC hold different positions on amendments of Markush claims in invalidation proceedings due to their different perspectives in the interpretation of the Markush claim. The PRB and BFIPC uphold “whole technical solution theory”, saying that the Markush claim is interpreted as a whole technical solution and deletion of alternative groups in the Markush formula is therefore not permitted. Contrarily, the BHPC accepts the “Parallel Technical Solution Theory”, holding that the Markush claim should be interpreted as a set of multiple parallel technical solutions and deletion of alternative groups in the Markush formula is allowable. Additionally, any limitation on amendments of Markush claims should be only to ensure that claims should not become specific compounds which not recited in the specification.

In order to resolve the disputes between the PRB and the courts, the SPC ordered a retrial on this case and issued its final judgement. The SPC judgement affirms the holdings of the PRB and explicitly negates the position of BHPC by holding that arbitrary deletion of alternative groups of the Markush claims is allowed. Also, the SPC proposes a standard for allowable amendments of Markush claims, that the amendments shall not generate compounds with a new function or effect. The holdings of the SPC are similar to the amendment principle of the Markush claims established by the European Patent Office in decision T1506/13[5]. The SPC does not seem to directly prohibit deleting the alternative groups of Markush claims, nevertheless, such an amendment can hardly be accepted during invalidation proceedings. This is especially true when the patentee plans to further distinguish the invention from the prior art by deleting the disclosed groups and selecting a class of compounds from Markush formula with new technical effects not recited in original specification. This will undoubtedly bring greater risks to patentees who are already in a passive position.

II. Suggestions

Obtaining stable Markush claims according to the suggestions from professional attorney may be advantageous to the patent applicant.

According to the rules established by the SPC in the Daiichi Sankyo case, it is believed that deleting alternative options in Markush claims will most often not be accepted by PRB. However, the Examination Department of SIPO informs that the rules have not been extended to prosecution proceedings. That is, in the substantive examination, the applicant still has the opportunity to narrow protection scope through deletion of alternative options and make the Markush claims more stable. Accordingly, the professionals who have extensive experiences both before PRB and Examination Department are required to provide good service to patent applicant. With full consideration of different amending manner of Markush claims during invalidation proceedings or prosecutions, a proper scope of Markush claims can be determined by our professionalism to minimize the risk of being invalidated in subsequent proceedings.