Regarding claim construction, China’s Patent Law only provides a very general stipulation that “the written description and the accompanying drawings may be used to explain what is claimed”. However, no further rules and criteria on claim construction are mentioned in the Implementing Rules of Patent Law and the Patent Examination Guidelines, which has actually caused considerable disputes in patent reexamination and invalidation proceedings.

The Supreme People’s Court recently adopts the broadest reasonable interpretation (BRI) standard in a patent invalidation administrative lawsuit. In its Administrative Judgment (2014) Xin-Ti-Zi No.17, the Court pointed out that:

In general, during patent reexamination and invalidation proceedings, broadest reasonable interpretation standard should be adopted for claim construction. That is, claims should be given broadest reasonable interpretation based on claim language in combination with the understanding of the patent description.Unless a claim term has been given a special definition in the written description, the term should be interpreted in a manner as would beunderstood by persons having ordinary skill in the art after reading the claims, written description and drawings, so as to avoid improperly restricting claim terms by using the written description or prosecution history. As such, a clearer conclusion on claim patentability and validity may be drawn that will in turn urge applicants to amend and perfect their patent application and enhance the quality of patent reexamination and invalidation.  

In this particular patent invalidation case, claim 1 did not specify the technical feature of “reflective film”, which instead appears in claim 10, a dependent claim of claim 1. The patent specification does not describe that the “full fiber-optic current sensor” must have a “reflective film” in the background of the invention. In view of this, the Supreme People’s Court held that it can only be construed based on the written description of the patent that the invention employs a fiber-optic coated reflective film in a preferred embodiment corresponding to dependent claim 10, not that the “full fiber-optic current sensor” of claim 1 contains such a technical feature. Thus, the Supreme People’s Court held that the invalidation decision No. 14794 interpreted the “full fiber-optic current sensor” of claim 1 in a restrictive manner by introducing the additional technical feature of its dependent claim and the content in the patent specification and wrongly applied the law. Hence the Court dismisses the invalidation decision No. 14794.