The Court of Appeal has upheld the High Court's decision in the famous "chocolate teapot" case, Illumina v MGI.(1) The sufficiency issues, which led to Birss J's use of the chocolate teapot analogy in discussing a "relevant range" and the refinement of the principles set out in the Supreme Court's decision in Regeneron v Kymab,(2) were not the subject of the appeal. However, the decision is of interest for clients in all sectors as it addresses whether the combination of two known features can be inventive ("collocation"), and provides some practical guidance concerning appeal procedure.


Illumina Cambridge Ltd (Illumina) is the proprietor of patents that relate to a method of DNA sequencing known as "sequencing by synthesis". Illumina sought to enforce five of these patents against Latvia MGI Tech SIA and Beijing Genomics Institute Group (collectively, MGI) on the basis that sequencing systems sold by MGI in the United Kingdom infringed Illumina's patents. Those patents all concerned the use of modified molecules and fluorescent dyes in the sequencing by synthesis process in circumstances where other sequencing processes had produced unsatisfactory results.

On 20 January 2021, High Court Judge Mr Justice Birss (as he then was) held that four of Illumina's patents relating to the DNA sequencing technology were valid and infringed, rejecting MGI's arguments that the patents were obvious or insufficient.(3) A fifth patent was held to be invalid and was not the subject of the appeal.(4)

In the High Court decision, Mr Justice Birss "recast" several of Lord Briggs's principles set out in the Regeneron v Kymab Supreme Court decision in more general terms, and in doing so, he confirmed that the Regeneron sufficiency principles apply to patented processes in addition to products.(5) For further details of the High Court case, see "Patents court illuminates sufficiency requirements".

MGI appealed Birss J's decision to the Court of Appeal. This was an opportunity to challenge Birss J's decision on sufficiency; however, the findings on sufficiency were not appealed. Instead, MGI challenged the findings on priority and obviousness.


On 17 December 2021, the Court of Appeal (Lord Justices Arnold, Nugee and Warby) unanimously dismissed MGI's appeal on all grounds, with Lord Justice Arnold delivering the leading judgment.

Mere collocation or inventive combination of known features?
Arguments in relation to collocation have arisen in a few cases recently, including, for example, Nicoventures v Phillip Morris,(6) and further development of the case law in this area are expected.

The collocation principle is that one cannot validly claim a "mere collocation" of two features that are each old or obvious. The principle has a long history, which Lord Tomlin set out in British Celanese v Courtaulds(7) in 1935, saying:

It is accepted as sound law that a mere placing side by side of old integers so that each performs its own proper function independently of any of the others is not a patentable combination, but that where the old integers when together have some working inter-relation producing a new or improved result there is patentable subject-matter in the idea of the working inter-relation brought about by the collocation of integers.(8)

One of Illumina's patents had been challenged at trial as well as on appeal as being a "mere collocation" of two old features. The basis for this argument was that the claimed invention had two elements, but there was nothing in the specification to indicate that these elements interacted in any non-obvious way.

Arnold LJ reviewed the case law and agreed with Birss J that the invention was not a mere collocation. He highlighted the importance of technical context when assessing whether a patent is a mere collocation. Arnold LJ noted that the judge had found that the skilled team would know from their common general knowledge that the building blocks which made up the claimed molecules might interact adversely when joined together and that the skilled term could not predict whether this adverse reaction would occur. However, the patent demonstrated no such adverse reaction. The Court of Appeal therefore held that the patent claimed a single invention that made a technical contribution to the art which was not obvious over the prior art.

MGI challenged Birss J's findings that the patents were not obvious. The Court of Appeal agreed with the trial judge that a previous research paper, called "Zavgorodny", which considered the synthesis of certain DNA-related molecules, was not in the same technical field as the patents in suit. It held that in light of the common general knowledge, the findings from this paper were "something to add to the organic chemist team member's general toolbox", but that this did not render the patents obvious because the paper was not in the same technical area.(9)

Arnold LJ had particular difficulty with MGI's obviousness challenge on the basis that "it merely amounts to a challenge to the judge's evaluation of these points without identifying any error of principle on his part".(10)

As such, the Court of Appeal decision serves as a salient reminder of the general reluctance of an appeal court to depart from the decision of a trial judgment unless there are identifiable errors of law or principle that provide reason to do so. This is especially the case when looking at the issue of obviousness where, as Lord Justice Arnold highlighted, the trial judge will have had the benefit of hearing and considering all of the evidence and arguments, including cross-examination of the expert witnesses, and the appeal bench will not.

In recognition of this factor, Arnold LJ said that:

Obviousness involves a multi-factorial evaluation and therefore this Court is not justified in intervening in the absence of an error of law or principle on the part of the judge . . . This is particularly so given that the decision was one of an experienced specialist patents judge after hearing extensive oral evidence from the experts in the field.(11)

As such, the Court of Appeal was not satisfied that Birss J had erred as a matter of principle or that he had misdirected himself as to the relevant legal test. In the result, the Court of Appeal found that the judge had made no error in his assessment of obviousness.

MGI also ran a priority squeeze argument on obviousness.(12) MGI argued at first instance that if the claimed inventions were not obvious over Zavgorodny, they were not entitled to claim priority from a Great Britain (GB) patent application. The basis for this was that the skilled team would be no better informed from a technical perspective after reading the GB patent application than Zavgorodny. Mr Justice Birss disagreed with MGI.

On appeal, MGI argued that Birss J's reasoning on priority was inconsistent with his reasoning on obviousness, or vice versa. However, the Court of Appeal upheld Birss J's finding.

The Court of Appeal held that certain features in the GB application provided more technical information than Zavgorodny, including, for example, detail concerning the appropriate experimental conditions. This, the Court found, would have led the skilled team to expect it to be plausible that the claimed compounds had the claimed utility.(13)

Respondent's notice
An important practical point arose in respect of the priority issues considered by the Court of Appeal. In his reasoning, Mr Justice Birss had proceeded on the basis that plausibility was required for priority, and, on appeal, Illumina argued in the alternative that he had been wrong to proceed on this basis.

Illumina argued that as the High Court had found in their favour, they did not need to file a respondent's notice raising this contention because the judge had made no decision adverse to Illumina concerning priority. The Court of Appeal disagreed.(14)

Arnold LJ's view here was clear, and it serves as an important reminder to practitioners in appeal proceedings that in order to ask the Court of Appeal to uphold a lower court's decision on different reasoning or for additional reasons to those given by the trial judge, a respondent's notice is required pursuant to rule 52.12(2)(b) of the Civil Procedural Rules.(15)


Given the impact of the first-instance decision, which further developed the evolving law of sufficiency, it is perhaps unsurprising that the Court of Appeal's decision has made far fewer ripples. However, it does provide important reminders for lawyers, as well as businesses operating in all sectors, about the task of an appellate court when considering the reasoning of a trial judge and the importance of ensuring that the appropriate procedural steps are taken in appeal proceedings so that the desired arguments can be advanced.

For further information on this topic please contact Nicole Jadeja, Sarah Taylor or Anna Harley at Pinsent Masons by telephone (+44 20 7418 8250) or email ([email protected], [email protected] or [email protected]). The Pinsent Masons website can be accessed at www.pinsentmasons.com.


(1) Illumina Cambridge Ltd v Latvia MGI Tech SIA & Ors [2022] EWCA 1924 (Civ).

(2) [2020] UKSC 27.

(3) Illumina Cambridge Ltd v Latvia MGI Tech SIA & Ors [2021] EWHC 57 (Pat) (20 January 2021) at [515].

(4) Id at [518].

(5) Id at [276]-[279].

(6) [2020] EWHC 1594 (Pat).

(7) (1935) 52 RPC 171.

(8) Id at 193.

(9) Illumina Cambridge Ltd v Latvia MGI Tech SIA & Ors [2021] EWCA Civ 1924 at [199].

(10) Id at [64].

(11) Id at [62].

(12) Id at [63].

(13) Id at [102], [106], [112]-[113].

(14) Id at [95].

(15) Id at [96].