Dutch Supreme Court ruling on claim interpretation in Resolution v AstraZeneca

The Supreme Court in the Netherlands has rendered an important decision on patent claim interpretation in the case Resolution Chemicals Ltd. v AstraZeneca B.V. and Shionogi Seiyaka Kabushiki Kasiha.

The case concerned the compound patent of rosuvastatin. Shionogi, the patentee, invented rosuvastatin and claimed "rosuvastatin and its pharmaceutically acceptable salts". In the description a definition of salts was included. This description involved a list of salts, without qualifying that the list was not exhaustive.

Resolution came up with a salt form of rosuvastatine containing a cation (zinc) which was not listed and claimed it was not infringing the patent. The District Court agreed with Resolution. The Court of Appeal however balanced the reasonable protection of the patentee and the legal certainty of third parties and ruled that Resolution did infringe the patent. On 8 June 2018, the Supreme Court confirmed the decision of the Court of Appeal.

This is an important judgment on claim interpretation and a confirmation that claims can be interpreted beyond their literal wording in the Netherlands. In this particular case, equivalence was not argued for strategic reasons (at that point in time the case-law on equivalence was extremely strict and the courts had more than once ruled that equivalents known at the filing date (in this case zinc salts) should have been included in the patent and could not be claimed later on by equivalence).

The case in more detail

This case relates to the scope of protection of a patent for a cholesterol inhibitor, more importantly whether or not the description of the patent provides for a limiting definition of the claim feature "pharmaceutically acceptable salt". The District Court ruled that this was the case. The Court of Appeal, however, did not agree with this. According to the Court of Appeal, the average skilled person would not take the definition given in par. 7 of the description of the patent (ie a list of salts) to be a limiting definition.

Resolution Chemicals then brought an appeal in cassation complaining about this. The Supreme Court, in addressing the complaints of Resolution Chemicals, first of all refers to established case law which states that the interpretation of patents is so closely interwoven with factual valuations, that it can only be reviewed in cassation to a limited extent.

The Supreme Court then refers to its decision in the Bayer/Sandoz case where it ruled:

"Article 69 EPC entails that the extent of the protection conferred by a patent is determined by the claims of the patent specification, in which the description and drawings are used to interpret those claims. (…)"

In accordance with this interpretation of the Protocol, the Supreme Court labelled the formulations used in its earlier rulings, "which is essential for the invention whose protection is invoked", and "the inventive idea underlying the words of those claims", as a point of view, as opposed to the literal text of the claims (the "extremes" in the words of the Protocol).

Identifying the inventive idea underlying the words of the claims serves to avoid an interpretation that is based exclusively on the literal meaning of the wording and therefore may possibly be too limited or unnecessarily broad for a reasonable protection of the patent proprietor.

In this scope, the description and drawings are an important source. Part of the description is a representation of the prior art that the applicant considers to be useful for understanding the invention (rule 42 of the Implementing Regulations to the EPC). Prior art that is not mentioned in the description may also be relevant. After all, the perspective of the average skilled person with his knowledge of the prior art is the guiding principle in interpreting a patent."

As to the question whether or not part of the protection has been "waived" in par. 7 of the description of the patent in suit and, more importantly, whether or not the waiver doctrine as formulated in the Van Bentum/Kool case – where the Supreme Court ruled that the average skilled person is only allowed to assume that protection has been waived if there would be valid reasons for such an assumption, taking into account the content of the patent in light of any other information that might be available, such as information from the prosecution file – is still applicable, the Supreme Court ruled that the inventive idea underlying the words of the claims only functions as a point of view, and no longer functions as a starting point.

In other words, the Van Bentum/Kool decision has no longer an independent significance as a separate test.

According to the Supreme Court, a judge can, in its search to balance the reasonable protection of the patentee and the legal certainty of third parties (as required both in the aforementioned case law and art. 1 of the Protocol) and confronted with the question whether the formulation in a claim needs to be considered as a limitation of the scope of protection, give meaning to the answer the average skilled person would give to the question whether there are valid reasons for such a limitation.

According to the Supreme Court, the Court of Appeal has explained the patent claims in light of the common general knowledge of the average skilled person and, contrary to the complaints raised by Resolution, it did not only take into account the inventive idea as a point of view, but also took into account the contribution of rosuvastatin to the art, the meaning and function of the salt forms in the rosuvastatin composition to be administered to a patient and the fact that the case concerns a compound patent that provides for absolute protection.

The Supreme Court confirms the decision of the Court of Appeal. In doing so, the Supreme Court follows the opinion of the Advocate General.