Swiss Supreme Court weighs in on K = Na

Entrance to the Swiss Federal Supreme Court

Since we are on the topic of K = Na, here a short update on the Swiss arm of the litigation.

The Swiss Federal Patent Court considered the prosecution history and denied infringement of Eli Lilly’s patent by equivalent means because of the limitation introduced by the patentee during the examination. Why the limitation was introduced was not relevant for the Patent Court. Good faith prevented a patentee from claiming protection for an embodiment that fell within the claim as originally filed, but not within the (literal) scope of the claim as granted. General principles of civil law, such that self-contradictory behaviour did not deserve protection ("venire contra factum proprium") applied also in patent law. While Article 69(1) EPC did not specifically mention the prosecution history as a means for the interpretation of patent claims, Article 69(1) EPC was not exhaustive and did not prevent considering general principles of civil law, such as good faith and abuse of law.

The Federal Supreme Court disagreed and granted Eli Lilly’s appeal against the decision. This is remarkable because the success rate of appeals to the Swiss Supreme Court is generally very low (about 13% overall, 20% if only taking into account appeals that are not dismissed on formal grounds), and the Supreme Court has also shown reluctance to enter into specifics of patent law in the past. In its decision of 20 October 2017, on the other hand, the Court delves into the technical details with verve.

For the Supreme Court, an exception to the principle that a patent claim can be infringed by equivalent means can only be based on abuse of law, and abuse of law was a measure of last resort, to be considered only to avoid "extreme injustice" ("krasses Unrecht"). The principle of venire contra factum proprium only sanctioned self-contradictory behaviour if third parties had relied on the previous (now contradicted) behaviour. The prosecution history was not a basis for a reliance interest of third parties. Denying infringement by equivalent means also when the limitation was introduced for compliance with Article 123(2) EPC contradicted Swiss law, which explicitly provides that infringement by equivalent means is to be considered infringement.

The Supreme Court then applied the standard equivalent infringement test developed by its case law (BGE 142 III 772). Of the three pronged test, only the third question posed any difficulties. The relevant third question was whether the skilled person would, after having read the patent (and not only the claim - the court here seems to deviate from earlier statements) would believe that the patentee had worded the claim, for whatever reason, such that infringement by equivalent means was not claimed ("ob der fachkundige Dritte bei objektiver Lektüre der Patentschrift zum Schluss gelangt, der Patentinhaber habe den Anspruch - aus welchen Gründen auch immer - so eng formuliert, dass er den Schutz für eine gleichwirkende und auffindbare Ausführung nicht beanspruche").

If a limitation was introduced for mere formal reasons, such as compliance with Article 123(2) EPC, one could not conclude that the patentee intended to exclude infringement by equivalent means based on the prosecution history. For the Swiss Supreme Court, similar to the German Federal Court of Justice, the reason why the limitation was introduced is therefore relevant. In the case at hand, reading the specification and the claim, the skilled person would not conclude that the patentee intended to exclude infringement by other salt forms of pemetrexed, although the claim only claimed the disodium salt of pemetrexed.