The Supreme Court in its latest decision ((2016) Zui Gao Fa Xing Zai No. 41) reversed the Beijing High Court's judgement of allowing the patentee to delete some definition of the groups in a Markush claim during the invalidation procedure, which further supported the Patent Reexamination Board's (PRB) consistent practice of rejecting amendments made to a Markush claim during an invalidation procedure.

In its decision, the Supreme Court stated that:

◆ A Markush claim is a generalized claim that defines multiple alternative elements, rather than a collection of numerous specific compounds;

◆ For fairness consideration, a Markush claim must be interpreted strictly;

◆ In order to prevent a patentee from unduly expanding the protective scope during claim drafting and to protect the reliance interest of the public, the general principle of making amendments to a Markush claim is that "the amendments should not result in a class of compounds or a single compound with new property or effect."

Analysis and comments

The judgment was made based on two key considerations: the first is to restrict and balance the power of a Markush claim, the second is to treat the patentee and the public fairly. The Supreme People's Court did not give detailed reasoning for its ruling. The implicit reasoning may consider the followings:

On one hand, armed with a Markush claim's strong ability to generalize, a patentee has the willing, either reasonable or unreasonable, to expand the protective scope of the Markush claim in order to seek for maximal benefits. If left unrestricted and unbalanced, the aforementioned action will inevitably result in unchecked patent rights, and seriously undermines the public interests. Therefore, while allowing a patentee to expand the protective scope of a Markush claim, it is reasonable to set balance checks such as adverse effects (i.e., unable to exclude the prior arts thus included).

On the other hand, a Markush claim is designed by the patentee, which has undergone several amendments before allowance. The public is treated unfairly if the patentee is allowed additional amendments during an invalidation procedure.

Accordingly, it is necessary to remind the patentee of the obligation to rationally design the Markush general formula, which in turn promotes the disclosure of more useful information of an invention. A patentee's failure to perform the obligation will lead to unfavorable consequences. For example, for the intermediate scope to be amended during an invalidation procedure, if the patentee had an opportunity to include it in the substantive examination but failed to do so, it shall be presumed that such intermediate scope was abandoned by the patentee; if the patentee did not foresee the intermediate scope, it belongs to a new matter that is not allowed to pursue. The rationality of the obligation lies in that: although it is impossible for the patentee to know all the prior arts and thus impossible to foresee all the intermediate scopes, the patentee has the ability to grasp the core content of the invention and thus has the ability to design suitable intermediate scopes based on the most important embodiments. In other words, if the most proper generalization of the most important core content does not exclude the prior arts, the invention per se may not possess novelty/inventiveness.

As for what amendments are allowed, it depends on the interpretation of "new property or effect." The Supreme Court believes that "Markush elements should be understood as a class of compounds with common property or effect." The Court's interpretation mainly considers the technical effect of the compounds, and the effect is set to the level of the worst compound demonstrated by working examples, rather than a range from the worst compound to the optimal compound. Thereby, if an amendment excludes compounds that are less active, the activity of the remaining compounds in the class is increased, which satisfies the Court's interpretation of "new property or effect." In addition, the "new property or effect" does not need to be "unexpected." Notes the Court's interpretation does not seem to address the non-obviousness issue.

Generally speaking, amending claims during an invalidation procedure are mainly due to supportive and inventive issues. For supportive issues, the problem is how to determine the activity of the structurally dissimilar compounds. As those compounds are regarded as inferior to the worst compounds demonstrated in terms of activity, excluding those compounds would nonetheless increase the level of "property or effect" of the remaining compounds. For inventive issue, similarly, if amendments result in compounds having superior activity, it can be said that such amendments generate "new property or effect." In theory, another possibility is that amendments only give structural differences without affecting the activity, which makes the remaining compounds more non-obvious in structure as compared with prior arts. The Supreme Court did not give a clear clue whether such amendments will be accepted. It may only be confirmed through individual cases in practice.

In conclusion, under the current practice, it is usually not allowed to eliminate certain definitions of the groups from a general formula, unless the general formula originally corresponds to several specific compounds.


After the issuance of the judgment, it became more unambiguous on whether amending a Markush claim during an invalidation procedure is permitted – generally, it only allows amendments such as deleting "ester". The patent applicants have to take certain countermeasures to offset the adverse effect of the judgment. We have the following suggestions.

Suggestions for drafting new patent application:

◆ In-depth understanding of the invention is the precondition, effectively disclosing the data is the key, actively analyzing the structure-activity relationship and considering the potential invalidation procedure in advance are the means;

◆ Searching for prior arts immediately before drafting;

◆ Sorting, categorizing and generalizing the working examples from two dimensions: structure and effect; and

◆ Setting the safest scope based on the optimal compounds, and designing as many levels of protective scopes as possible;

Suggestions for patent applications entering into China and during prosecution:

◆ Taking the initiative to voluntarily redraft the patent application (as stated above);

◆ Adding "intermediate scopes" based on the optimal compound (re-generalization);

◆ Amending claims to include the safest scope if adding claims is not allowed; and

◆ Creating opportunity to file further divisional applications so as to keep the patent family pending for important cases, taking into account that the amendment during prosecution is more flexible than that during invalidation.

In summary, in spite of this unfavorable judgment, patentees and their representatives can take preventative actions, such as designing the scope of the patent more wisely, to get prepared for the challenges in the future.