Beaker and Bunsens: A numbers game? – Infringement of numerical claims following Actavis v Eli Lilly

13 February 2019

A recently reported case in the High Court of England and Wales has shed further light on how patent claims are being interpreted in the UK following the 2017 landmark decision of the Supreme Court in Actavis v Eli Lilly.

In Regen Lab SA v Estar Medical Ltd & Ors, claimant Regen was the proprietor of European patent EP2073862 with claims covering a method for the preparation of blood plasma enriched in platelets and other factors (known as platelet rich plasma or PRP). Regen accused various respondents of infringement of the patent by supplying kits in the UK which were subsequently used to prepare PRP according to the claimed method. The defendants counterclaimed for revocation of the patent.

Although the patent was ultimately found to be invalid for lack of novelty and inventive step, Judge Hacon expressed an opinion that, if the patent had been found valid, it would have been infringed. In his decision, Judge Hacon discussed the application of the doctrine of equivalents, introduced by Actavis v Eli Lilly, to the interpretation of numerical values in claims.

By way of background, prior to Actavis v Eli Lilly, the practice of the UK courts was to determine patent infringement on the basis of a purposive construction of the claims as they would have been read by a person skilled in the art. Infringement was found if the product or process fell within the scope of the claims on the basis of this construction.

Following the Actavis decision, however, the test for infringement is now divided into two steps. The first step involves determining whether the alleged infringement falls within the scope of the claims on the basis of normal interpretation. If the alleged infringement does fall within the scope of the claims on that basis, infringement is proven and the assessment stops. However, if the alleged infringement does not fall within the scope of the claims on the basis of normal interpretation, it is now necessary to assess whether the so-called variant nevertheless infringes because it differs from the claimed invention in only an immaterial way. This is referred to as applying the doctrine of equivalents. Actavis v Eli Lilly set out a series of questions to be considered when applying this doctrine. In the Actavis case, application of the doctrine led to the finding that pemetrexed dipotassium was equivalent to pemetrexed disodium as claimed.

Returning to Regen Lab v Estar Medical, the claim in question required centrifuging blood in a separator tube containing a polyester-based thixotropic gel and a buffered sodium citrate solution at 0.10 M. The defendants’ process made use of a thixotropic gel which contained Tris (2-ethylhexyl) trimellitate and a buffered sodium citrate solution at 0.136 M. It was found that there would be no infringement on the basis of a normal interpretation of the claims, as Tris (2-ethylhexyl) trimellitate is not a polyester and 0.136 M is considered to be sufficiently different from 0.10 M, as would be expected when considering the number of decimal places or significant figures usually taken into account in the interpretation of numerical claim limitations.

However, following Actavis, the Court went on to assess whether infringement could nevertheless be proved on the basis of the doctrine of equivalents. In this assessment, Judge Hacon had to consider two key points: first, how the doctrine should be applied when there are multiple differences between the alleged infringement and the claim; and second, whether the doctrine applies to numerical values. The defendants, in particular, had argued that the doctrine should not apply in relation to a numerical claim.

In respect of the first issue, Judge Hacon concluded that the key question is whether the accused product or process is a variant falling within the scope of the claim taking all equivalents into account. Although it may be convenient to consider each equivalent one by one, there must be a single overall answer in relation to each accused product or process.

In respect of the second issue, the Court concluded that the approach to claims containing one or more numerical limits should be no different to that applicable to any other type of claim, and that principle was not changed by the decision in Actavis v Eli Lilly. Furthermore, Judge Hacon stated that to require strict compliance with a numerical limitation in a claim would put numerical claims into a special class, as strict compliance is not necessarily required of any other type of claim limitation.

Judge Hacon then went on to conclude that the inventive concept of the patent claim is exploited in substantially the same way as to achieve substantially the same result if the process uses a non-polymeric thixotropic gel and the sodium citrate buffer solution has a molarity of 0.136 M instead of 0.10 M. This fact would have been obvious to the skilled person at the priority date. Further, Judge Hacon thought that the molarity of the solution in particular was not essential to the inventive concept, such that strict compliance with the literal meaning of the claim would not have been intended. Accordingly, it was found that the respondents would have infringed the patent based on the doctrine of equivalents, had the patent been valid.

This case highlights the potentially far-reaching effects of the Actavis decision. Last year in Icescape v Ice-World, the Court of Appeal also found, by applying the Actavis doctrine, that a series arrangement of manifolds in a mobile ice rink would infringe a claim explicitly reciting a parallel arrangement. These decisions suggest that the UK’s lower courts will continue to apply the doctrine of equivalents to all claim features, including chemical species, the arrangement of mechanical components, and numerical limitations, at least until further guidance from a higher court is received.

Michael Ford

Michael Ford

Trainee patent attorney

Haseltine Lake Kempner - Cookie Disclaimer

Our website uses cookies to provide you with a better online experience. If you continue to use our site without changing your browser settings, we'll assume you are happy to receive cookies. Please read our Cookie policy for more information.

Do not show this message again