On 20 March 2025, the UK High Court delivered its judgment in DSM IP Assets BV v Algal Omega 3 Ltd [2025] EWHC 675 (Pat). The case relates to patents for microbial oils which can be a source of DHA, an omega-3 fatty acid which is an important component in baby formula. The Claimants (“DSM”) and Defendants (“Mara”) are competing producers of such oils. Mr Justice Mellor found that of the three patents that DSM asserted against Mara only one (now expired) was valid and infringed.
The lengthy judgment raises a number of interesting legal issues and practice points.
Product-by-process claims
DSM applied to unconditionally amend claim 1 of EP 3 530 740 (“EP740”), its patent for a new microbial oil, as follows:
1B. A microbial oil comprising a triglyceride fraction of at least 70% by weight, wherein the docosahexaenoic acid content of the triglyceride fraction is from at least 50% 55% to 65% by weight, and wherein the oil comprises 5% by weight or less of heptadecanoic acid, wherein the microbial oil is a crude oil extracted from the biomass of a microorganism without further processing, and wherein the microorganism is a thraustochytrid microorganism.
Mellor J held that the added claim features (underlined above) constituted process steps relating to the history of the product. The EPO does not allow such product-by-process claims unless there is no other way to define the claimed product (see e.g. Case Law of the Boards of Appeal, 10th ed., II.A.7.3 and T 150/82). The same approach applies in the UK, including when considering amendments (Hospira v Genentech [2014] EWHC 3857 (Pat)).
In this case, Mellor J held that DSM could instead have designated relevant characteristics of the microbial oils it sought to claim – e.g. their fatty acid profile. As such, the proposed amendments resulted in a claim that was unclear and not allowable, both because it did not allow the skilled team to understand the claimed oils’ characteristics, and because it was possible to define the claimed oils by way of product characteristics.
Further, even if the amendments had been allowed, they would have been disregarded for the purpose of assessing obviousness.
It is established law that a product is not new merely because it is made by a new process. Therefore, the process features of a product-by-process claim are to be disregarded when assessing novelty (although not for infringement) (Kirin-Amgen v TKT [2004] UKHL). Birss J (as he then was) commented obiter in Hospira v Genentech that the same should hold true for obviousness. Mellor J followed that logic in this case and held that the amended claim would have been obvious over a prior art reference, Fabritius.
Biogen insufficiency: Relevant ranges
EP740 was also found to be invalid for breadth of claim insufficiency because the amended claims extended to oils from all thraustochytrid microorganisms, whereas DSM’s inventive contribution was a single thraustochytrid strain.
DSM argued that the patent was not required to enable the claimed product for all thraustochytrids, because this was not a “relevant range” following Regeneron v Kymab [2020] UKSC 27 (Lord Briggs’ judgment at [56](vii)):
“… The requirement to show enablement across the whole scope of the claim applies only across a relevant range. Put broadly, the range will be relevant if it is denominated by reference to a variable which significantly affects the value or utility of the product in achieving the purpose for which it is to be made.”
However, the evidence established that the fatty acid profiles of oils from different thraustochytrids varies widely (e.g. regarding DHA-levels), so that it could not be said that all thraustochytrid oil would have the same value and utility. Indeed, Mellor J found at [581] that “EP740 does precisely nothing to help the skilled person with the task of finding other high-DHA thraustochytrids, which is a huge burden”. There was therefore a relevant range which was not enabled.
Claim construction: Numerical precision
DSM’s EP 2 576 801 (“EP801”) claimed an oil extraction process including a step of “raising the pH of the lysed cell composition to 8 or above”. DSM’s case was that “8 or above” should be interpreted as covering pH values of 7.5 or above.
DSM contended that treating numbers in claims as being precise to the number of decimal places used in the claim has become an established convention, citing Smith & Nephew Plc v ConvaTec Technologies Inc [2015] EWCA Civ 607, and the subsequent decisions in Napp v Dr Reddy’s [2016] EWHC 1517 (Pat) (Arnold LJ) at [90]–[95], upheld on appeal at [2016] EWCA Civ 1053. However, Mellor J considered that Smith v Nephew and the judgment of Floyd LJ in Jushi Group Co., Ltd v OCV Intellectual Capital, LLC [2018] EWCA Civ 1416 instead make it clear that there is no such rule. Rather, the general principles of construction apply to numerical ranges.
Taking a purposive approach, Mellor J held that all target pH ranges in the specification must be read in the same way and since parts of the description set out pH ranges in increments of 0.5 (7, 7.5, 8, 8.5 etc), it was not possible to interpret the whole number pHs as including the value 0.5 units below.
Further, the word “raising” in the claim suggests a movement of the pH so that it is above 8. Mellor J found that the skilled team would understand this suggestion, since they would expect the cell lysis step of the claims to have the effect of lowering pH. Therefore “8 or above” meant exactly that.
Ultimately, this point was not decisive in finding EP801 to be obvious over a prior art citation, Kobzeff.
Approach to expert evidence
Mellor J made serious criticisms of Mara’s expert, finding that his evidence was infected by hindsight, and he had failed to properly understand the concept of the CGK and the need to avoid speculation. Mara, accepting that his evidence was unsatisfactory, did not seek to rely on it and instead tried to found its case on the evidence of DSM’s experts.
This may have been fatal to Mara’s case on obviousness of EP 2 921 155 (“EP155”), the only patent held to be valid (although now expired), infringement having been admitted. Mellor J commented that with “better expert evidence”, which gave a reason why the skilled team would focus on oil production using enzymatic cell lysis without hindsight, he may have found EP155 obvious over a prior art patent application.
This serves as a cautionary tale when selecting a testifying expert. Even where, as here, an expert has an impressive CV and “very considerable experience” in the relevant field, it is essential to ensure that they also have a secure grasp on the correct legal approach to their evidence and will maintain that approach under the pressure of cross-examination.
