Although China is not a common law jurisdiction, the decisions of authorities such as the Patent Re-examination Board (PRB) and the courts are nonetheless worthy of review. These decisions not only illustrate trends in the authorities’ practice, but also provide guidance on patent application drafting and prosecution in China.

This chapter focuses on certain key issues in the life sciences sector in light of several recent cases, with practical considerations to help practitioners and patent owners alike to better understand the IP situation in China and be more proactive in patent drafting, prosecution and invalidation.

Doctrine of equivalents

An accused product or process infringes the patent rights of a claim if it includes technical features which are identical or equivalent to all of the technical features of the claim. After an element-by-element analysis, if an accused product or process includes technical features identical to those of the claim, a literal infringement will be found; if one or more technical features in the accused product or process are equivalent to those of the claim and the rest are identical, infringement under the doctrine of equivalents will be found.

‘Equivalent feature’ is interpreted as “the feature which performs substantially the same function in substantially the same way to obtain substantially the same result, and which could be conceived by a person skilled in the art without inventive efforts”.

The cases in which the doctrine of equivalents is applied are very limited, especially in the life sciences sector.

In the recent decision in Anhui Tuote Biological Engineering Co, Ltd v Beijing Zhongsheng Jinyu Diagnostics Technology Co, Ltd (2016), the Zhejiang High Court provided guidance on how to apply the doctrine of equivalents.

In this case, Claim 1 of the patent at issue (owned by Jinyu Diagnostics) related to a colouring method by reacting Gly-Arg-beta-naphthylamide with particular chromogenic reagents. In the accused method of Tuote Biological, Gly-Arg-4-methoxy-beta-naphthylamide and the same chromogenic reagents were used. Gly-Arg-4-methoxy-beta-naphthylamide is a 4-methoxy modification of Gly-Arg-beta-naphthylamide.

Jinyu Diagnostics accused Tuote Biological of infringing its patent rights under Claim 1 pursuant to the doctrine of equivalents. Tuote Biological argued that Gly-Arg-4-methoxy-beta-naphthylamide was not equivalent to Gly-Arg-beta-naphthylamide due to estoppel. The key issue was thus whether Gly-Arg-beta-naphthylamide was equivalent to Gly-Arg-4-methoxy-beta-naphthylamide.

The courts at first and second instance both held that Tuote Biological had infringed the patent rights of Jinyu Diagnostics under the doctrine of equivalents and upheld Jinyu Diagnostics’ claims. In particular, the courts opined that Gly-Arg-beta-naphthylamide was equivalent to Gly-Arg-4-methoxy-beta-naphthylamide, based on the following analysis:

  • The colouring result of the patented method was achieved by beta-naphthylamine, the cleavage product of Gly-Arg-beta-naphthylamide; while in the accused method it was obtained by 4-methoxy-beta-naphthylamine, the cleavage product of Gly-Arg-4-methoxy-beta-naphthylamide. The group 4-methoxy was not involved in the colouring reaction. Tuote Biological provided no evidence of any improvement on the colouring and testing result by Gly-Arg-4-methoxy-beta-naphthylamine in view of Gly-Arg-beta-naphthylamide.
  • Therefore, both the accused method and the patented method achieved the same colouring function through the same reaction mechanism and there was no substantial difference in terms of testing effect.
  • Moreover, the replacement of two substances could be conceived by a skilled artisan without inventive efforts.

Based on these facts, the courts concluded that Gly-Arg-beta-naphthylamide was equivalent to Gly-Arg-4-methoxy-beta-naphthylamide.

A criterion similar to inventive step is applied in the determination of equivalent technical features. In this case, had Tuote Biological provided evidence that the colouring result produced by the substance substituted with the methoxy group was significantly different from that of the patent at issue, the court would have come to a different conclusion.

Prosecution history estoppel

Prosecution history estoppel is a limitation on the doctrine of equivalents and prevents the patentee from using equivalence to recapture coverage that was surrendered during prosecution or an invalidation procedure of the parent application and divisional application thereof. The surrendered coverage includes that which is abandoned through observation or claim amendments.

In Tuote Biological v Jinyu Diagnostics the courts held that prosecution history estoppel did not apply. This finding was based on the fact that the granted Claim 1 was actually the original Claim 3, because it was obtained by incorporating original Claim 3 into Claim 1. If the original Claim 3 was considered separately, no limitation was made to the element Gly-Arg-beta-naphthylamide, which was only present in the claim. Therefore, no coverage regarding Gly-Arg-beta-naphthylamide was surrendered through amendments. Moreover, the patentee did not expressly disclaim any specific technical solutions during the prosecution. Therefore, no estoppel applied to the equivalence of Gly-Arg-beta-naphthylamide to Gly-Arg-4-methoxy-beta-naphthylamide, from either claim amendments or observation.

As seen in this case, in applying estoppel, attention should be paid to the specific technical solution abandoned by the patentee through claim amendment or observation. Claim amendments may not necessarily bring forth estoppel for a specific technical feature.

In an earlier case – Hubei Wushi Pharmaceutical Co, Ltd v Aonuo Pharmaceuticals (2009) – the Supreme Court provided guidance on how prosecution history estoppel prevents the patentee from using equivalence to recapture coverage that was surrendered during prosecution.

In this case, the accused infringing product contained calcium gluconate and the granted claim related to a product containing active calcium. The ‘active calcium’ in the granted claim was amended from ‘soluble calcium’ during prosecution.

The accused product did not literally infringe the patent right, as ‘active calcium’ did not cover calcium gluconate. According to the original description of the patent at issue, ‘soluble calcium’ included calcium gluconate, active calcium and other calcium salt. From the description, ‘active calcium’ did not cover calcium gluconate.

However, the accused product also did not infringe the patent right under the doctrine of equivalents. The court held that that amendment from ‘soluble calcium’ (general term) to ‘active calcium’ (specific term) to overcome the non-support issue in the prosecution constituted estoppel. Through such limitation, the patentee actually abandoned other technical solutions of soluble calcium aside from active calcium and the abandoned technical solutions of soluble calcium included calcium gluconate. Therefore, the court held that the patentee was not allowed to recapture the abandoned technical solution of calcium gluconate in subsequent infringement and that calcium gluconate was not equivalent to active calcium.

In light of Tuote Biological v Jinyu Diagnostics, patentees are advised to formulate a number of dependent claims in order to avoid triggering the potential estoppel by claim amendments in subsequent litigation; for example, when claim amendment becomes necessary in prosecution, the amendment is achieved by choosing one of the dependent claims as basis for further prosecution, instead of by further limiting one of the independent claims or dependent claims.

As seen in Hubei Wushi Pharmaceutical Co, Ltd v Aonuo Pharmaceuticals, claim restriction during prosecution limits the application of the doctrine of equivalents. Under current practice, arguments of disclaimer or restricting claims contributing to the allowance of a patent right will trigger the application of estoppel. Therefore, close attention should be paid to arguments or claim amendments that would result in expressly surrendering technical solutions during prosecution or an invalidation procedure.

Markush claims

Markush claims, as a special drafting method, are commonly used in pharmaceutical patent applications. Such a claim is often referred to as a ‘claim covering parallel alternatives’, in that all the technical features are either formulated as being selected from a collection of a series of options or directly defined as a series of options in parallel.

Although Markush claims are widely used, the interpretation of a Markush formula compound claim or a Markush claim covering a genus compound is a subject of dispute.

The PRB has held that a Markush formula compound claim is essentially a generalisation of a technical solution based on specific embodiments and protected as a whole technical solution. In Invalidation Decision 16266, for example, deletion of some Markush alternatives from definitions of a certain variable in a Markush formula compound claim was not allowed in the invalidation procedure. This was based on the fact that such amendment did not constitute deletion of a technical solution, because a Markush formula compound claim is interpreted as a whole technical solution. During the invalidation procedure, claim amendment is limited to deletion of a technical solution, deletion of claims and combination of claims.

This dispute was temporarily resolved by the Beijing High Court in 2013. The court opined that a Markush formula compound claim is a set of parallel technical solutions.

However, in a recent case the Beijing IP Court took a different opinion. In Gilead Sciences, Inc v PRB (2016) the court held that a Markush claim constitutes a whole technical solution, rather than a set of several parallel technical solutions – thus taking the same position as the PRB.

The independent claim of the patent at issue related to a Markush formula compound. Among the definitions for the variables of formula, some alternatives were not described in the priority document. The priority document disclosed a Markush formula compound with a narrower scope and the subsequent formal application claimed a broader scope covering the narrower scope.

One of the key issues was how to interpret a Markush formula compound claim. If it is interpreted as a whole technical solution, the subsequent broader scope is a technical solution that is independent of the earlier narrower scope and cannot enjoy the priority of the earlier narrower scope. However, if it is interpreted as a set of parallel technical solutions, at least the overlapping technical solutions of the subsequent broader scope can enjoy the priority (ie, partial priority) of the earlier narrower scope.

During the invalidation procedure, the PRB took its usual position that a Markush formula compound claim should be interpreted as a whole technical solution and the subsequent broader scope cannot be entitled to (partial) priority. Dissatisfied with the PRB’s decision, Gilead appealed to the Beijing IP Court.

The Beijing IP Court opined that a Markush formula compound claim constitutes a whole technical solution. In its judgment, the court explained why a Markush formula compound claim should not be regarded as a set of parallel technical solutions in light of the novelty requirements for a selection invention or numerical range as prescribed in the relevant guidelines.

With regard to a selection invention, for example, a narrower-scope invention which is not disclosed in the prior art is obtained by selecting from a broader scope in the prior art. The selection invention will be allowed if such selection achieves an unexpected technical effect. If a Markush formula compound in the prior art is construed as a set of parallel technical solutions, any technical solution selected from this scope will be considered as disclosed and will not possess novelty. Such an interpretation of a parallel technical solution for a Markush formula compound claim would diverge from the guidelines.

From the above, a dilemma can be seen in the interpretation of Markush claims. If a Markush claim is interpreted as a whole technical solution, there will be no room to amend the claim by deleting Markush alternatives during the invalidation procedure, because the amendment method is very strict during this procedure. Another important issue raised by such an interpretation is partial priority. The so-called ‘poisonous divisionals/priority’ issue continues to arise in China, although it was recently settled by the European Patent Office (EPO). In late 2016 the EPO Enlarged Board of Appeal issued an order in connection with Referral G1/15 (partial priority/poisonous divisionals), whereby partial priority was not refused for Markush claims.

If a Markush claim is interpreted as a set of parallel technical solutions, it is impossible for an applicant to obtain a selection invention based on an application with Markush alternatives. The Markush alternatives disclosed in the prior application will destroy the novelty of the subsequent selection application.

Considering the uncertainty of construction of Markush formula compound claims and the difficulty of making claim amendments during the invalidation procedure, significant care should be taken when drafting patent applications containing Markush claims, especially Markush formula compound claims.

To avoid the dilemma over Markush claims, when drafting a patent application which constitutes a basis for claim amendment during prosecution or a priority document for a subsequent application, it is recommended that more technical solutions be described for subsequent prosecution claim amendments or the priority basis. The primary strategy is to provide an array of intermediate ranges of scope in an inverted pyramid manner, in addition to a broad scope of technical solutions. Another strategy for providing more options for subsequent prosecution claim amendments or priority basis is to separately define each variable of the Markush formula compound, layer by layer.

For example, with regard to a Markush formula compound including variables R1 and R2, R1 can be further divided into sub-class R1A, R1B and so forth, where each sub-class is defined separately. R2 can be drafted in the same way. At the same time, a statement can be included in the description that “the present invention also includes the technical solutions by combing any one of (R1A, R1B… and R1H) with any one of (R2A, R2B… and R2H)”, so as to include any combination of each variable. A cross-table may also be provided to achieve the above objective. The two strategies may be used together in one patent application.

When drafting claims, layer-by-layer protection of a Markush formula compound in an inverted pyramid manner is recommended, so as to provide more opportunities to withstand the challenge from invalidation requests.

If any new developments arise in view of priority documents, it is recommended to pursue the newly developed technical solution and the technical solution enjoying the priority separately, so as to avoid potential priority issues.

Conclusion

The Chinese authorities’ patent guidance is particularly helpful, from the early stages of drafting and prosecution to the later stages of invalidation and litigation.

In light of prosecution history estoppel, patentees are advised to formulate a certain number of dependent claims by picking one dependent claim as the basis for further prosecution when claim amendment becomes necessary, so as to avoid triggering the potential estoppel by claim amendments. Attention should also be paid to arguments which would result in expressly giving up technical solutions during prosecution or an invalidation procedure.

Considering the uncertainty of construing Markush formula compound claims, it is recommended that more genus technical solutions be described for subsequent prosecution claim amendments or priority basis, by either providing an array of intermediate ranges of scope in an inverted pyramid manner or separately defining each variable of the Markush formula compound layer by layer and providing multiple combinations of the variables.

Liu, Shen & Associates

Hanhai Plaza (1+1 Plaza), 10th Floor

10 Caihefang Road, Haidian District

Beijing 100080

China

Tel +86 10 6268 1616

Fax +86 10 6268 1818

Web www.liu-shen.com

Guojun (Jason) Liu

Partner

mail@liu-shen.com

Guojun (Jason) Liu is a partner at Liu, Shen & Associates. He specialises in patent prosecution, re-examination and invalidation and patent-related administrative litigation and infringement lawsuits, especially in the fields of chemistry, cosmetics, food, material science, biology, pharmaceuticals, pesticides, chemical engineering and medical devices.

Dr Liu started his IP career with Liu, Shen & Associates in 2007. He has represented several large international companies in renowned invalidation cases. He also does significant work in preparation of patent infringement, validity and freedom-to-operate opinions.

Dr Liu obtained a BS in chemistry and a PhD in organic chemistry, both from Fudan University (China). Moreover, he obtained an LLM in IP law from John Marshall Law School.

Zongliang (Stephen) Zou

Partner

mail@liu-shen.com

Zongliang (Stephen) Zou is a partner at Liu, Shen & Associates. He assists clients in matters involving all types of IP right, focusing on patent prosecution and patent administrative and judicial litigation. Dr Zou is experienced in preparing patent infringement, validity and freedom-to-operate opinions and counsels clients in various matters relating to IP rights and drug regulatory matters.

Dr Zou started his IP career with Liu, Shen & Associates in 2003. Before this, he was involved in pharmaceutical research. Dr Zou obtained a PhD in pharmaceutical chemistry from the Chinese Academy of

This article first appeared in IAM. For further information please visit www.IAM-media.com.