Sean Hutchinson

July 2026

In 2017, the UK Supreme Court issued a landmark judgment setting out how it believed the UK should apply the so-called “doctrine of equivalents” when deciding on infringement of a patent. This judgment was handed down in the case of Actavis v Eli Lilly and the test for assessing equivalence (set out by Lord Neuberger in the written decision) has thus become known as the “Actavis test”.

This test, set out at paragraph 66 of the decision, is as follows:

“i) Notwithstanding that it is not within the literal meaning of the relevant claim(s) of the patent, does the variant achieve substantially the same result in substantially the same way as the invention, i.e. the inventive concept revealed by the patent?

ii) Would it be obvious to the person skilled in the art, reading the patent at the priority date, but knowing that the variant achieves substantially the same result as the invention, that it does so in substantially the same way as the invention?

iii) Would such a reader of the patent have concluded that the patentee nonetheless intended that strict compliance with the literal meaning of the relevant claim(s) of the patent was an essential requirement of the invention?

In order to establish infringement in a case where there is no literal infringement, a patentee would have to establish that the answer to the first two questions was “yes” and that the answer to the third question was “no”.”

In the 9 years since the Actavis test was established, it has been applied to many different cases where infringement by equivalence is at issue. However, few (if any) decisions have provided as clear guidance on how this test is to be correctly applied in practice as a recent decision of the UK Court of Appeal (Salts v Pelican, a link to which is provided above).

In this case, Salts sued Pelican for infringement of its UK patent relating to ostomy bags, which are used to collect and store human waste emanating from a stoma. The patent was unusual because it contained 10 independent claims. Salts accused Pelican of infringing two of them.

All 10 independent claims required that the claimed appliance comprises “weld portions” that extend away from the appliance, but only 5 of them (including the two Pelican was alleged to infringe) required those weld portions to extend “downwardly towards a bottom of the appliance”. Pelican’s allegedly infringing product comprised “lobes” which extended outwards from the periphery of a bag, but arguably not downwards towards its bottom (the lobes each had a part which sloped downwards, but the lobes as a whole did not extend down towards the bottom of Pelican’s product).

The Court of Appeal first considered whether the “lobes” of Pelican’s product constituted weld portions that extended downwards towards a bottom of the product, in which case there would have been literal direct infringement and thus no need to consider infringement by equivalence. Ultimately, the Court decided, by applying the well-established principles of purposive construction, that the claims required each weld portion as a whole, not only a part thereof, to extend downwards towards a bottom of the appliance. Thus, the Court held there was no literal direct infringement.

The Court then had to consider whether, despite there being no literal direct infringement, Pelican’s “lobes” should be considered equivalent to Salts’ “weld portions”, and thus held to infringe under the doctrine of equivalents.

To do this, the Court applied the Actavis test, and began by formulating the inventive concept as follows:

“… the provision in an ostomy appliance of weld portions additional to the peripheral connection… which are positioned and shaped (i) so as to force waste up rather than out, so that the waste is distributed more evenly along the length of the bag, thereby reducing bulging and sagging, and (ii) so as to avoid trapping waste above them.”

The Court then applied Question 1 of the Actavis test. In doing so, the Court held the burden of proof for demonstrating that Pelican’s “lobes” achieve substantially the same result in substantially the same way as Salts’ “weld portions” rests with Salts as the proprietor of the patent. The Court then held Salts had met this burden of proof and thus answered Question 1 with “yes”.

Neither Salts nor Pelican disputed that if Question 1 were answered with “yes”, then Question 2 would have to be answered with “yes” as well. Thus, the Court did not consider this Question in detail.

In then applying Question 3, the Court had to consider whether the skilled person would have understood that Salts had intended that strict compliance with the requirement for each weld portion as a whole to extend “downwardly towards a bottom of the appliance” was an essential requirement of the invention.

However, to apply this Question to the facts of the case before it, the Court noted it first needed to consider how this Question should be applied. The Court thus considered this point and held in its decision that:

• the answer to Question 3 is not a factual assessment, but a question of interpretation of the patent specification, and thus neither party bears a burden of proof,
• the default assumption must be that strict compliance with the claim wording is not intended, otherwise Lord Neuberger would not have included the word “nonetheless” when drafting Question 3,
• to reach a different conclusion to this default assumption, there must therefore be a “good reason” why the skilled person would have concluded that strict compliance with the claim wording is intended, and
• the mere fact that the variant in question is not encompassed by the claim as construed is inadequate to constitute such a “good reason”.

The Court then applied these principles to the facts before it, and noted that:

• the claims are formulated in structural terms, not functional terms, suggesting the specific structural features are important,
• the technical advantages attributed to weld portions having the ‘downwardly extending’ feature in the description are not attributed to weld portions having other configurations, suggesting this configuration is important,
• the fact there are 10 independent claims suggests Salts had carefully drafted the claims to capture different embodiments, pointing towards strict compliance with the wording of each claim being intended, and
• the ‘downwardly extending’ feature is found in some independent claims but not others, suggesting it was intended to limit those independent claims in which it is found.

In the Court’s view, these were four “good reasons” why the skilled person would have concluded that Salts had intended strict compliance with the literal meaning of the claim wording. The Court thus answered Question 3 with “yes” and held there was no infringement under the doctrine of equivalents.

Conclusions

The decision in Salts v Pelican provides helpful guidance regarding the application of Questions 1 and 3 of the Actavis test.

As a decision of the Court of Appeal, this decision is binding on future decisions of the High Court (including both the Patents Court and the IPEC), is likely to be followed by future decisions of the Court of Appeal itself, and can only be overturned by a decision of the Supreme Court or a change in the law introduced by Parliament. It is therefore likely the principles established in Salts v Pelican will be applied in cases regarding infringement by equivalence for the foreseeable future, especially since the three Lord Justices of the Court of Appeal (Lord Justices Newey, Arnold, and Miles) were unanimous in their decision.

Thus, in particular, proprietors of UK and European (UK) patents would be wise to note that they bear the burden of proof for demonstrating that an allegedly infringing variant achieves substantially the same result in substantially the same way as the invention. Likewise, third parties wondering whether their products may constitute infringing variants of inventions patented in the UK should note the courts will only insist upon strict compliance with the claim wording if the specification provides a good reason for doing so.

It will be interesting to see how these principles are applied to other cases in the future!