When is the limitation of the claims relevant?

With Pemetrexed the highest national courts in Europe have re-evaluated the requirements for equivalent patent infringement. After Germany and the United Kingdom, the Supreme Court in Switzerland has now also revised the criteria for adjudicating equivalence and limited the relevance of the prosecution history. Contrary to its intention to align Swiss law regarding equivalent patent infringement with Germany and the United Kingdom, there remain important differences. With this PharmaCircular, we keep you abreast of the recent developments on equivalent patent infringement in Switzerland.

According to the doctrine of equivalence a product or process can infringe a patent, even if it is not covered by the literal meaning of the patent claim. Over the last few years, the Swiss courts adopted a three-step test to assess equivalent patent infringement, similar to the one practiced in Germany:

  1. Does the replacing feature objectively fulfil the same function as the replaced feature?
  2. Starting from the teaching of the patent in suit, is it evident to the skilled person that the replacing feature has the same technical effect as the replaced feature?
  3. With due consideration of the claim language and in light of the description: Would the skilled person have taken the replacing feature into account as an equivalent solution?

The second question is not to be confused with the inventive step assessment. For equivalent patent infringement one does not compare with the general state of the art but with the teaching in the patent in suit. Consequently, it should not matter whether the replacing feature is inventive in light of the state of the art. After Pemetrexed, as discussed in more detail below, it is questionable whether this principle still applies.

Based on this three step test, the Swiss courts first compare the claimed feature with the replacing feature and second, ask whether the same effect would be evident to the skilled person.

The first instance decision

Eli Lilly's patent claims the use of disodium salt of pemetrexed in combination with vitamin B12 for the treatment of cancer. During prosecution Lilly narrowed the claims twice, first from antifolates to pemetrexed, and later from pemetrexed to the disodium salt of pemetrexed.

As in other jurisdictions the Swiss affiliate of Actavis (today Teva), sought a declaration of non-infringement for pharmaceutical products with pemetrexed diacid (non-salt), peme­trex­ed dipotassium or pemetrexed ditromethamine rather than pemetrexed disodum.

In the first instance, the Swiss Federal Patent Court (SFPC) denied an equivalent patent infringement. In view of the claims and in further consideration of the specification, the skilled person would have understood that the claims were strictly limited to pemetrexed disodium. Pemetrexed disodium is a highly specific chemical compound. This particular term, used in the claims, contrasts with the broad wording in the specification for other compounds, such as antifolates or vitamin B12. Thus, without going into the prosecution history but merely by reading the claims in light of the specification the court concluded that the skilled person would indeed have understood that Lilly deliberately limited its claims to pemetrexed disodium.

Further, the SFPC rejected the relevance of Lilly's argument that the core of the invention is the combination with vitamin B12 which makes pemetrexed suitable for anti-cancer treatment. According to the court the inventive concept is of no use in infringement proceedings. Either there is literal or equivalent patent infringement or no infringement at all.

The Supreme Court reversed

The Supreme Court did not agree with the SFPC's conclusions and modified the test for equivalent patent infringement.1

First question: Same effect

Siding with the SFPC, the Supreme Court assessed whether the replaced feature fulfils the same objective function. Actavis' products were approved in an abbreviated procedure as a generic version of Lilly's pemetrexed disodium. Because the marketing approval for a generic requires bioequivalence, the Supreme Court concluded that the active substance conjugated with a different salt fulfils the same function.

Second question: Discoverable

Even though the Supreme Court reached the same conclusion, it did not follow the SFPC's reasoning: Based on his general knowledge, the skilled person would have understood that pemetrexed diacid would have the same effect as pemetrexed disodium. In addition, the use of a free acid and the ditromethamine or dipotassium salt was well established at the priority date. To have this confirmed was a matter of routine experiments.

The Supreme Court's reasoning conflicts with previously well-established principles assessing of the second question on equivalent patent infringement:

  1. First, the Supreme Court relies on the skilled person's understanding at the priority date rather than at the infringement date. This reliance contrasts with established case law according to which the understanding at the infringement date is relevant.
  2. Second, the Supreme Court denied that a replacing feature is discoverable to the skilled person if it is inventive. In support of this reasoning the Supreme Court relied on an earlier 1998 decision ("variant is irrelevant unless it is based on a new inventive concept").[1]

Third question: Equal value

By rejecting the SFPC's reasoning on the deliberate limitation, the Supreme Court was of the opinion that Lilly did not waive its rights to claim protection against equivalent embodiments when it narrowed its patent claims during prosecution. Such limitation may not be acknowledged because of Lilly's actions in response to the examiner's objections and irrespective of the underlying reasons. The finding of a deliberate limitation must be compliant with the principles for the construction of contracts:

"[…] the lower court correctly found that the patent applicant must remain committed to a deliberate limitation. However, this requires that the limiting wording must be understood to mean that the patent applicant abandoned the right to claim equivalent patent."


In Germany, to avoid an unfair result, the doctrine of equivalent patent infringement is a means for including an immaterial variant into the patent's scope of protection, even if that variant falls outside of the claim's language. It was always understood that equivalent patent infringement was the exception rather than the rule.

No such reservation can be found in the Supreme Court's decision. To the contrary, the Supreme Court opens the door for debating the inventive concept that is not restricted by the claim's wording. A deliberate limitation may not be assumed based merely on a comparison between a broader application and a narrower granted patent. Rather, such limitation shall be acknowledged only if there is evidence that the patentee intended strict compliance with the literal meaning of the patent claims. To prevail, third parties will need sound arguments to explain why the patentee would not have meant to include a variant in the patent. The result of this approach is that even more attention must be given to what is disclosed in the specification.

The proceedings between Actavis and Eli Lilly – as in other jurisdictions - were based on non-infringement; there was no counterclaim for invalidity. An invalidity counterclaim can prevent the court from construing the claims too broadly, bringing them in line with the actual disclosure. In fact, the Supreme Court alludes to this when it indicates that the disclosure of a patent should not be confused with its scope of protection. This is, however, only half of it: Disclosure matters when sufficiency is challenged.

Another important issue is the Supreme Court's reliance on the skilled person's understanding at the priority date rather than the infringement date. Thus, technological advances not envisaged at the priority date do not fall under the patent's scope of protection. If the variant was unforeseeable at the priority date, the variant is not equivalent. Unclear is whether this was intended by the Supreme Court in that it contradicts the findings of Lord Neuberger, indicating that the infringer might be entitled to a new patent: "I find it hard to see why that alone should prevent the resultant variant to infringe".

This article was first published by the International Law Office, a premium online legal update service for major companies and law firms worldwide. Register for a free subscription.

[1]   Judgement of 20 October 2017 in the appeal of Eli Lilly vs. Actavis Switzerland AG re pemetrexed (procedure 4A_208/2017) setting aside the decision of 9 March 2017 (O2015_004). For an English translation click here.