On 21 January 2021, Deputy High Court Judge Nicholas Caddick Q.C. handed down judgment in patent litigation proceedings between Coloplast A/S (“Coloplast”), the Claimant, and Salts Healthcare Limited (“Salts”), the Defendant.

Coloplast alleged that Salts infringed its patent, EP (UK) 2 854 723 (“Patent”) by selling the Salts’ Confidence BE ostomy bag. Salts counterclaimed for revocation of the Patent on the grounds of lack of novelty, obviousness by lack of inventive step, insufficiency, AgrEvo obviousness and added matter. The subject of the Patent relates to ostomy collection bags, which are used to collect waste discharged from the human body. The Patent claimed the invention of an integrated textile construction used for the comfort layer of these ostomy bags.

By trial, Coloplast focused on a single claim of the Patent for infringement. This claim was dependent on various combinations of four antecedent claims. Ultimately, Caddick QC found that the Patent was invalid for lack of inventive step over the common general knowledge (“CGK”) and the prior art documents, but was not invalid on the remaining grounds. Notwithstanding this, Caddick QC held that Salts’ product launched in 2017 did infringe the Patent should his findings revoking the Patent later be found incorrect on appeal.

Three factors are central to Caddick QC’s decision to invalidate the Patent on the grounds of lack of inventive step:

  1. consideration of what amounted to CGK at the priority date;

  2. the correct application of the test for inventive step; and

  3. assessment of whether the alleged inventive concept of the Patent involved an inventive step over the GCK, or any of the prior art cited by Salts.

Common general knowledge

Caddick QC first considered the nature of ostomy bags on the market on or before the priority date in 2012. There were three types of ostomy bags that collected human waste from different parts of the body. These were typically made to include or connect to a flange and would be closed or drainable. Ostomy bags were commonly constructed by combining a barrier film, made up of up to five layers with what was known as a comfort layer. Comfort layers had initially been separate and removable, but by the priority date, manufacturers often integrated the comfort layer into the construction of the ostomy bag. The alleged innovative aspect of an ostomy bag’s construction, which was the subject of the Patent, was Coloplast’s use of a woven material for the integrated comfort layer. Coloplast argued that this was inventive, as although use of woven materials for non-integrated comfort layers and integrated comfort layers made out of non-woven fabric were both well-known at the priority date, there was no evidence that a woven integrated comfort layer had actually been incorporated in any design at that point in time.

Salts’ expert evidence was that there was no reason why the skilled person would have tried to use a woven material for an integrated comfort layer in 2012. Importantly though, his reasoning for this was that the invention would not have been pursued for practical rather than technical reasons. Woven material was much more expensive to use than plastic, required a greater amount of plastic in the barrier layer, which was considered less environmentally friendly, and was less adaptable than non-woven materials.

Test for inventive step

Caddick QC began by identifying the tension inherent in the statutory definitions of inventive step. Salts argued that the wording of s.1(1)(b) Patents Act 1977 requires the invention to positively involve an inventive step. Coloplast meanwhile pointed to s.3 Patents Act 1977, which states that “an invention shall be taken to involve an inventive step if it is not obvious to a person skilled in the art having regard to any matter that forms part of the state of the art by virtue only of section 2(2).

Caddick QC agreed with Salts’ interpretation, citing Jacob LJ’s example of a 5¼ inch plate in Actavis UK Limited v Novartis AG [2010] EWCA Civ 8. This is that a new limitation applied to existing CGK or prior art, which is purely arbitrary and has no technical advantage shall be treated as obvious because it is not inventive.

Further, again citing Jacob LJ in the above case, Caddick QC held that for the purpose of establishing obviousness, it is enough to show that the concept of the invention would have occurred to the skilled person. The skilled person is not required to actually have implemented that idea, which they may not have done due to other commercial considerations.

Application of inventive step test to CGK and prior art

In relation to inventive step over CGK, Caddick QC held that the Patent suggested using a material known to the skilled person in a way that was known to be possible. Further in Caddick QC’s view, the skilled person would not have thought using a woven material for an integrated comfort layer as being unlikely or difficult to achieve in technical terms, nor that techniques used for welding of non-woven materials would not have worked in the same way, subject to some adjustment and experimentation, for woven materials. Caddick QC instead found that the reasons why woven materials had not been used for the integrated comfort layer at the priority date was the greater costs, changes to machinery and systems of manufacturers of ostomy products and enhanced environmental concerns associated with using woven material in their construction. In the process, Caddick QC dismissed Coloplast’s submissions that subsequent market uptake of integrated woven comfort layers indicated that the Patent must have been inventive. He did so on the basis that Coloplast had not accounted for commercial factors such as product marketing and sponsored stoma nurses as being the significant factors behind the subsequent uptake.

Second, Coloplast submitted that the Patent contained three previously unrecognised technical advantages of using the woven material in an integrated comfort layer. In each case Caddick QC held that the Patent had not provided any technical advantage, which would not have been obvious to the skilled person at the priority date. This is highlighted neatly by one of the technical advantages that Coloplast submitted that Patent offered, specifically the greater resistance to tearing. Although Caddick accepted that the use of woven material did in fact offer greater resistance to tearing, he held that the skilled person would have been well aware through the CGK that a woven material would offer greater resistance to external forces due to its interlaced structure, and was therefore an obvious consequence of its use.

Having held that the Patent was invalid for lack of inventive step over the CGK, Caddick QC separately held that the Patent was also invalid on the grounds of lack of inventive step over each prior art document advanced by Salts. In approaching a number of the prior art documents, Caddick QC considered that Coloplast’s counsel had approached the assessment of inventive step in a manner that was contrary to Pozzoli and the further case law clarifying the skilled person’s motivations. Coloplast counsel had done so by advancing inventive step on the basis of what the skilled person would have done or been motivated to do reading the prior art, rather than considering whether the relevant step of the Patent would have been obvious to the skilled person.

Practical tips

Lastly, two practical tips can be extracted from Caddick QC’s judgment. These are that when submitting any experiments, it is important that these are conducted, even in their preparatory stages solely by the expert(s). In this case, Salts’ expert defended his team’s use of scissors in cutting samples, however he had not overseen how the cutting had taken place, or was in a position to confirm that the cutting had been carried out in a way that minimised damage to the samples. The result of this was, as Caddick QC noted, that when compared together Salts’ samples were significantly more damaged than Coloplast’s. In declining to admit this fact, Caddick QC found that this introduced an element of concern about Salts’ expert evidence.

Second, Caddick QC criticised the quality of Salts’ images produced by scanning electron microscopy that were included in the trial bundles. In particular, finding that they were less easy to interpret than Coloplast’s. In the end, Caddick QC found that he had no reason to doubt Salts’ expert evidence of what the images showed. Cumulative small factors such as this can give a judge concern about an expert’s evidence, which ultimately could prove to be more determinative to the eventual outcome.