Intellectual Property Enterprise Court

Claim No: IP-2023-000054 - [2025] EWHC 563 (IPEC)

Fecha: 14-Mar-2025

The Law

The Law

31.

Henry Carr J summarised the law in relation to the identification of the hypothetical construct of the PSA in Hospira UK Limited v Cubist Pharmaceuticals LLC [2016] EWHC 1285 (Pat) relied on by the Defendant and again in Garmin (Europe) Ltd v Koninklijke Philips NV [2019] EWHC 107 (Ch) relied on by the Claimant. There is no dispute as to the principles. Patents are directed to those likely to have a real and practical interest in the subject matter of the invention, which includes devising the invention itself as well as putting it into practice. The PSA has practical knowledge and experience of the field in which the invention is intended to applied, and reads the specification with the common general knowledge of persons skilled in the relevant art, knowing that its purpose is to disclose and claim an invention. The PSA may be a team of people with different skills, or may be a single hypothetical person, to whom the patent is addressed, but each such addressee is uninventive and unimaginative.

32.

As Birss J (as he then was) stated at [58] of Illumina Cambridge Ltd v Latvia MGI Tech SIA [2021] EWHC 57 (Pat), [2021] RPC 12, the concept of the PSA applies in two distinct circumstances, the first being the person to whom the patent is addressed and whose attributes, skills and common general knowledge will be necessary to implement the patent, who is always the appropriate PSA from the point of view of addressing sufficiency, since the patentee is entitled to put together his invention by combining any skill-sets he likes. The second, described by Birss J at [59] of Illumina as “the one relevant to obviousness”, is said by him to be “In nearly all cases… the same as the first kind”, but may not be, and was not in the case of Schlumberger Holdings Ltd v Electromagnetic Geoservices AS [2010] EWCA Civ 819, [2010] RPC 33. Birss J explained in Illumina at [59] – [64]:

[59]… The question then is what are thelegal principles which define the identity of the second kind of skilled person.

[60] One principle in Schlumberger was identified in [65]:

“In the case of obviousness in view of the state of the art, a key question is generally “what problem was the patentee trying to solve?” That leads one in turn to consider the art in which the problem in fact lay. It is the notional team in that art which is the relevant team making up the person skilled in the art.”

[61] This will be the governing approach in many cases but it can lead to trouble. There are cases of so called “problem-inventions” in which simply asking if the solution is obvious given the problem is unfair because inventiveness lay in identifying the problem. The fact the solution was obvious once you identify the problem does not prove a lack of inventive step in such a case. In fact experience shows that real cases are often more nuanced in that there can be aspects of a problem which are not common general knowledge and so one cannot always draw a sharp line between problem invention cases and other cases.

[62] Furthermore, blindly applying an approach based on the definition of the problem to be solved could lead to a very narrowly defined skilled person and that can create its own difficulties, which were well described by Peter Prescott Q.C. in Folding Attic Stairs Ltd v Loft Stairs Co Ltd [2009] EWHC 1221 (Pat); [2009] F.S.R. 24. He showed why it could be wrong to frame the art in a narrow way. At [33]-[34] he said:

“33.
Common general knowledge is quite different. It is what people skilled in the art actually do know, or ought to know, provided that knowledge is regarded as sound. Common general knowledge is not a phrase used in the Patents Act or the European Patent Convention. It would be difficult to define the person skilled in the art in this case, or the common general knowledge, because so far as I know there is no recognised profession or calling of designing folding attic stairways. …It is unfair to define an art too narrowly, or else you could imagine absurd cases e.g. “the art of designing two-hole blue Venezuelan razor blades”, to paraphrase the late Mr T.A. Blanco White. Then you could attribute the “common general knowledge” to that small band of persons who made those products and say that their knowledge was “common general knowledge” in “the art”. That would have the impermissible result that any prior user no matter how obscure could be deemed to be common general knowledge, which is certainly not the law.
34.
However it does not make much difference in this case, because the amount of special knowledge that is required to understand the patent in suit is not great. I would identify the person skilled in the art as one who has practical experience as a manufacturing carpenter, assisted by a metal fabricator. At the date of the patent (1996) this person or team would be vaguely aware of folding stairways in general terms, at most. The actual construction of old Stira, while known to many customers, was not common general knowledge in the art, in my judgment.”

[63] So while Folding Attic Stairs neatly explains one of the difficulties, given its facts the judge did not have to identify a principle to be applied to solve it. Furthermore, while too narrow a definition could be unfair to the inventors, it could be just as wrong and unfair to the public to define a team so widely that their common general knowledge is so dilute as to make something seem less obvious than it really was (see Pumfrey J. in Mayne Pharma Ltd v Debiopharm SA [2006] EWHC 1123 (Pat) at [3]-[4]).

[64] The other principled approach from Schlumberger to identifying the second kind of skilled person is to look at what is really going on in the art up to and at the priority date (Jacob LJ at [42]):

“I think one can draw from [Dyson v Hoover] that the Court, in considering the skills of the notional “person skilled in the art” for the purposes of obviousness will have regard to the reality of the position at the time. What the combined skills (and mind-sets) of real research teams in the art is what matters when one is constructing the notional research team to whom the invention must be obvious if the Patent is to be found invalid on this ground.”

33.

Birss J acceded to a test proposed by Illumina, namely to require “something which could properly be called an established field at the priority date. Depending on the facts the field could be a research field… or a field of manufacture as in Folding Attic Stairs” (at [66]), which he described at [67] as “a principled way of solving the problem identified in Folding Attic Stairs”, saying:

“If the design and manufacture of folding attic stairs in particular was an established field then there is nothing unfair in defining the skilled person in that way. But if not then the wider definition (general carpenter plus metal fabricator) is appropriate. In other words, the width of the field in which the skilled person operates for the purposes of obviousness (a.k.a. the “art in which the problem lay” (per Schlumberger) is ultimately governed by what was actually going on up to the priority date. It is not primarily a function of the invention itself, the problem to be solved, nor the patent’s text.”

34.

He concluded at [68] that in a case where it was necessary to define the PSA for the purposes of obviousness, the approach of the Court should be:

To start by asking “What problem does the invention aim to solve?” (clarifying at [69] that this was an objective exercise);

ii)

Next to consider what the established field which existed was, in which the problem in fact can be located (clarifying at [70] that how wide the definition of that field should be will depend on the facts and what was going on in reality, and should be established as an exercise in hindsight: “It does not matter at this stage if those in that field at the priority date did not perceive the particular problem or did not perceive it in the manner it is now characterised”); and

iii)

Determining that it is the notional person or team in that established field which is the PSA.

35.

I have also been taken by the Claimant to the Court of Appeal judgment in Illumina which upheld Birss J on this issue ([2021] EWCA Civ 1924, [2022] RPC 14), and Illumina at first instance was approved and applied in Modernatx Inc v Pfizer Ltd [2024] EWHC 1695 (Pat), relied on by the Claimant, and Alcon v Actavis [2021] EWHC 1026 (Pat) (referred to at [115] of Modernatx) which emphasised that there was an element of value judgment in the assessment as the Court was required (i) not to be unfair to the patentee by allowing an artificially narrow definition, per Illumina at [62] and (ii) not to be unfair to the public (and the defendant) by going so broad as to “dilute” the common general knowledge (Mayne Pharma Ltd v Debiofarm at [4]).