Patent law in Switzerland: Are numeric ranges excluded from the doctrine of equivalence

When are patent claims with numbers or measurements infringed? Can competitors be held liable for patent infringement if their product has characteristics outside the claimed range? The Swiss Federal Patent Court addressed these questions in two judgments, but to the opposite effect. First, in preliminary injunction proceedings, the court found infringement by equivalent means for a tablet with an amount of the active ingredient that was outside the claimed range. In the main proceedings, however, the court came to the opposite result and denied a patent infringement.

How could this happen?

The dispute concerned a medicinal product for the treatment of iron overload resulting from blood transfusions in patients with anemia. Novartis originally marketed the drug as a dispersible tablet. In October 2019, it changed the formulation to a swallowable tablet. The new formulation eliminated the need to dissolve the tablet in water or an aqueous solution.

Novartis is the owner of European patent EP 2 964 202, which claims protection for a swallowable film-coated tablet containing deferasirox or a pharmaceutically acceptable salt thereof in an amount of 45% to 60% by weight based on the total weight of the tablet, plus other excipients not of further interest here.

Teva's Swiss subsidiary launched a tablet containing 64.3% deferasirox, always based on the total weight of the tablet. The amount of the active ingredient was thus above the claimed range of 45% to 60% by weight. All other requirements were indisputably fulfilled. This raised the question of the significance of numerical ranges in a patent claim when a product was alleged to have infringed the patent claim despite having a different feature.

Like features described in words, numbers and measurements are part of the binding force of a patent claim. They are decisive in determining the scope of protection of a patent, but also in limiting it. Since general terms in language always contain a certain degree of abstraction, numbers and measurements have a higher degree of unambiguity and clarity. Therefore, competitors can generally assume that patent claims set out everything for which protection is sought. Accordingly, exceeding or falling short of these features is not considered to be patent infringement. These are the general principles. But the case of deferasirox turned out differently.

How do the Swiss courts apply the doctrine of equivalence?

In its decision of 15 December 2021, the Swiss Federal Patent Court found infringement for a tablet containing 64.3% deferasirox, even though the patent claim was limited to 45% to 60% by weight of this active pharmaceutical ingredient. A three-judge panel made the decision in a preliminary injunction proceeding.

In its reasoning, the court first clarified that there can be no literal infringement of the patent claim:

"If a measured value is outside a claimed numerical range, the value is no longer covered by the wording of the patent claim".

The Court further reasoned that the claim does not contain any qualifying indication to the effect that the claimed numerical range is not strictly limited, such as by the statements "substantially" or "approximately in the range of". In addition, the range of 45% to 60% by weight was not given as an example.

When examining patent infringement by equivalent means, Swiss courts assess whether the modified feature is sufficiently different from the claimed feature. In the case of the deferasirox formulation, an assessment was made of the relevance of the different amount of the active ingredient in the total weight of the tablet (64.3% instead of 45% to 60% by weight of deferasirox). The Swiss courts apply the following three-pronged test, which is similar but not identical to case-law in other European jurisdictions:

• Equal effect: Does the modified feature perform the same function as the claimed feature?
• Accessibility of the modified feature: Was the same effect of the modified feature apparent to the skilled person?
• Binding on the wording of the patent claim: Would a skilled person, on reading the patent specification, conclude that the patentee deliberately drafted the claim so narrowly as to waive protection for an equal and apparent embodiment? In assessing this question, due regard must be given to legal certainty.

In the preliminary injunction proceedings, the court concluded that a value outside the claimed range was nevertheless within the scope of the patent because it was within accepted tolerances. In this case, it would be of no technical significance to adhere exactly to this value. With respect to deferasirox, the Federal Patent Court found that the contested tablet was within the accepted tolerances for pharmaceutical formulations. Taking into account the total weight of the tablet, the accepted tolerance was 7.5% by weight. With an upper limit of 60%, this would give an upper limit of 68% by weight.

Sixteen months later, the Swiss Federal Patent Court came to the opposite conclusion and denied an equivalent patent infringement also in the case of deferasirox. The decision was made in the ordinary proceedings by a five-judge panel (i.e. with two additional judges than the preliminary injunction panel). In its decision of 20 April 2023, the court ruled that in the case of a formulation patent for deferasirox, the doctrine of equivalence does not allow for an extension of the claimed range in favour of generally accepted tolerances:

"Because the skilled person assumes that the patentee has already taken into account possible tolerances when defining the claimed range. If it [the patentee] wanted to cover embodiments that are even further away from the preferred value of 56%, it should have defined the claimed range more broadly".

According to the court, this was all the less likely since the description disclosed a preferred active ingredient of 56% by weight. Because this preferred value was closer to the upper limit of the claimed range, the upper limit of 60% had to be binding:

"Although it is not normally relevant where within the claimed range the preferred value is lies, it is noteworthy in the present case that the upper limit of 60% is significantly closer to the preferred value of 56% than the lower limit of 45%. If the patentee had claimed an equally wide range above and below the preferred value, the range would be 46% to 66%. The fact that the upper value is closer to the preferred value may be taken by the skilled person as a further indication that the amount of active ingredient cannot be increased any further and that 60% is a critical limit to be respected".

From this, the court concluded that the patentee had specifically and bindingly placed the claimed range around the preferred numerical value (i.e. the patentee had deliberately specified the invention within this range and thus dispensed with the scope of protection lying outside this range). Accordingly, the court held that a medicinal product containing 64.3% by weight of the active ingredient could not fall within the scope of protection of the asserted claims. The skilled person would be entitled to assume that the patentee had waived protection for embodiments with less than 45% or more than 60% of the active ingredient by weight.

The sticky question

The judgment is not yet final. It is likely that the Federal Supreme Court will have to rule in this matter as well. For reasons of legal certainty, this decision is to be welcomed. It preserves confidence in the limiting effect of a patent claim. For the time being, competitors can now rely on the fact that claimed numbers and measurements are likely to be conclusive and binding. However, the decision does not mean that the doctrine of equivalence is not applicable to patent claims with numerical ranges. In its reasoning, the court placed great emphasis on the fact that the preferred embodiment was not in the middle of the claimed range. It is uncertain whether the court would have reached a different result if no preferred embodiment had been disclosed in the patent. The decision therefore does not yet settle all questions.

It appears that the court already had a perceptible difficulty with its decision in the preliminary injunction proceedings. Nevertheless, it did not balance the effects of a preliminary injunction on the parties. The risk of an unjustified preliminary injunction is thus borne unilaterally by the defendant. This is all the more so because the requirements for claiming damages for an unjustified preliminary injunction are high in Switzerland. Except in cases of abuse of rights, Swiss courts rarely award damages to a party that was wrongly enjoined. Against this background, the question arises as to whether the Federal Patent Court granted a preliminary injunction too lightly by disregarding the effects on the defendant. In Switzerland, it is sufficient for a preliminary injunction to be granted if the patent holder is threatened with a disadvantage that cannot be easily remedied. In the case of medicines that are reimbursed by the compulsory health insurance in Switzerland, this requirement is affirmed without further ado. The negative effects of a preliminary injunction are thus not sufficiently taken into account.

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