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China: Patents: Supreme Court rules on use of specification in claim construction

According to Article 59 of the Chinese Patent Law the specification and drawings related to a patent right may be used in claim construction. However, it has long been a question as to whether claims are to be construed based on claim language alone without referring to the specification and drawings, or whether the content of the specification and drawings shall be read to limit or otherwise be used to illustrate the scope of claims. In a recently decided case (number 2016-XingZai-70), the Supreme Court of China held that the content of the specification and drawings was not allowed to be read into the claims, and that claims were to be construed in a narrow sense.

Facts of the case

The case arises from a patent invalidation proceeding, resulting in three rounds of judicial review – courts of first and second instances and the Supreme Court for retrial. Claim 1 of the patent in suit said that an oil feed pump provides pressure oil to a pump wheel and a turbo via a pipeline. Throughout the proceedings, the parties differed heavily on the positional relationship between the oil feed pump and a hydraulic coupler, because claim 1 never specified whether the oil feed pump was located inside or outside the hydraulic coupler.

The Beijing High Court held that as it is hard to understand the positional relationship between the components solely by reading the claims, the specification and drawings must be relied on to determine the claimed solution accurately. According to the two drawings of the machine, the oil feed pump is clearly outside the hydraulic coupler system. Additionally, the patent specification stated that the hydraulic coupler was changed from a variable speed mode to a fixed speed output mode by making improvements to the interior of the hydraulic coupler, that is the shaft drive of the conventional main oil feed pump into which the hydraulic coupler inputs is removed, and a main oil feed pump driven directly by a separate motor is installed outside the hydraulic coupler and it is connected to the outlet duct of the conventional main oil feed pump. It is stressed that the main oil feed pump is specially designed to work with the hydraulic coupler. Relying on this information, the Beijing High Court ruled that persons having ordinary skill in the art would undoubtedly determine that the oil feed pump in claim 1 is located outside the hydraulic coupler, the feature of which is not disclosed by the prior art reference cited. In this case, the Beijing High Court used the specification to limit the meaning of the claim.

The Supreme Court disagreed. The judges held that claim 1 may cover two scenarios: the oil feed pump is located outside or inside the hydraulic coupler. They found that it cannot be determined from the claim language that the oil feed pump must be located outside the hydraulic coupler. Although the oil feed pump is located outside the hydraulic coupler in the specification and drawings, the content in the specification and drawings cannot be construed as a technical feature of the claimed invention. The judges of the Supreme Court pointed out that the Beijing High Court erred in reading the relevant content of the specification and drawings into claim 1 and thus substantially changed the claims during claim construction. This, according to the Supreme Court, was against the relevant laws and regulations. It seems that the Supreme Court judges believed that the specification was merely illustrative of the scope of claims, instead of setting out additional claim elements.

Controversy over use of specification in claim construction

This recent case has provoked some controversy and discussion about how to use the written description for construction of a patent claim. Some professionals believe that the ruling of the Supreme Court judges in this case is inconsistent with the mainstream claim construction theory and the precedents of the Supreme Court. Others think that the scope of claims, as determined solely based on the claim language, will become overly broad and unreasonable, against some of the international norms, for example, the broadest reasonable interpretation (BRI) of the USPTO. The consequences are obvious: a patentee in an infringement case might obtain a scope unduly broader than what he or she is entitled to get; on the other hand, the patentee in the invalidation procedure may face more risks due to broader claim construction.

A particular concern about this Supreme Court ruling is its impact on invalidation. Where the claim language is found to be indefinite and may cover several scenarios, even if one of the scenarios is emphasised as the inventive step of the patent or some of the scenarios are implied to be undesired, the claim cannot be construed in a narrow sense to a prior art challenge. Considering that patentees have limited opportunities to amend claims during the invalidation procedure, and there is no patent reissue mechanism in China so far, a patent now faces a higher possibility of being invalidated due to overly broad claim construction. These concerns are something the patent owners have to watch closely and take into consideration when drafting their claims.

Steve Song

Eleanor Zou

AnJie Law Firm26/F, Tower D, Central International Trade Center6A Jianguomenwai Avenue, Chaoyang District, Beijing 100022, PR ChinaTel: +86 10 8567 5988Fax: +86 10 8567

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