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Patents Court finds ostomy bag patent invalid for lack of inventive step

Posted on 12 March 2021

In Coloplast v Salts Healthcare, the Patents Court decided that Coloplast's European Patent (UK) 2 854 723 was invalid on the basis that the concept claimed in the patent – the use of a woven material for an integrated 'comfort layer' of an ostomy bag - was obvious over the common general knowledge, as well as five pieces of prior art. The Court rejected Salts' attacks based on novelty, insufficiency, AgrEvo obviousness and added matter. The infringement claim relating to Salts' "Confidence BE" range of ostomy bags launched in 2017 also failed as the patent was found invalid (the infringement claim would have succeeded if the patent had been found to be valid). The patent is also under attack at the European Patent Office, where (in a decision under appeal) it was found to be invalid for lack of novelty over certain prior art.

The Patent and the Common general knowledge

The invention relates to a textile comfort layer of an ostomy bag (an ostomy bag connects to a stoma, an opening in a human body created surgically to allow the discharge of body waste) providing it with an increased resistance against tearing and pulling forces. In particular, a textile comfort layer is added to a barrier film such that, in the area/s of attachment, some but not all of the fibre filaments of the comfort layer are embedded in the barrier film material. This has been of particular benefit with drainable ostomy bags because it results in a bag that is more resistant to the increased forces of friction and tension on such bags.

The Court conducted a review of the common general knowledge as at the priority date of the patent 25 May 2021, i.e., information that would have been widely known to those engaged in the art and regarded by them as a good basis for further action. The key dispute was as to whether the use of woven (as opposed to non-woven) fabric for integrated comfort layers was common general knowledge. Whilst the Court accepted that the actual use of such material in integrated comfort layers was not a matter of common general knowledge, the possibility of using such a woven material was. Using woven material had not been pursued however because it would involve significant additional cost. Further, because it would involve more plastic, it was undesirable environmentally. There was also no particular problem with existing ostomy bags with non-woven integrated comfort layers.  


The inventive concept of the patent was that a woven fabric could be used and welded in such a way to form an integrated comfort layer with improved properties. The Court concluded that this was not inventive as at May 2012 when viewed in light of the common general knowledge described above. It was common general knowledge that a woven fabric could be used to make an integrated comfort layer and the skilled person would not have seen it as being unlikely or difficult to achieve in technical terms – the Court highlighted that this was not a case where the idea was to use a material in an unexpected or unanticipated way. Essentially, the reasons woven materials had not been used previously were of a commercial nature rather than a technical one: the greater cost of materials and the costs associated with changing machinery and systems, and also the environmental concerns. Whilst woven products sold by Coloplast and Salts now account for 24% of the market, this was explainable because, in more affluent markets such as the UK, manufacturers have concluded that the commercial disadvantages are surmountable with appropriate marketing.

In addition to obviousness over the common general knowledge, the Court also found that the relevant claims of the patent lacked inventive step over certain prior art, including an earlier Salts product.

Other findings

The Court rejected the novelty attack (based on the same prior art) and the added matter attack (which had been based on the difference between the words 'not all' in the application, as opposed to 'some, but not all' in the patent as granted when discussing the extent of the fibre filaments being embedded in the barrier film material). Insufficiency arguments raised as a squeeze were also rejected. The Court had found there was no inventive step because it was well-known that a woven fabric could be used in such a way as claimed by the patent, and because the means of achieving the requirements of the relevant claims 1-4 involved using materials and techniques that were part of the common general knowledge. This meant that the disclosure of the patent was not insufficient. The Court also rejected an argument based on uncertainty, where Salts had argued that the patent failed to teach the skilled person how to ascertain whether the surface of the comfort layer in the zone(s) of attachment has the same tactile and visual characteristics as its surface outside such zone(s).

Finally on validity, Salts ran an argument based on AgrEvo obviousness i.e., that the claims of the patent went beyond its alleged technical contribution – an argument described by Salts as occurring at the boundary of obviousness and insufficiency. Whilst the Judge's starting point was that this argument did not add anything to the grounds of obviousness over the common general knowledge and insufficiency, he went on to reject it. Salts argued that the contribution reflected in claims 1-4 of the patent were not something that all wovens offer, as it would depend upon the nature and specification of the material used and the welding conditions, none of which were specified in the claims. However, the Judge decided that Coloplast's claimed technical contribution did not relate to all uses of all wovens but was restricted to the use of wovens in a way that would meet claims 1 to 4 of the patent. 

Had the patent been valid, the Court would have found Salt's Confidence BE products to infringe.


Interestingly, having found the patent to be obvious, trial judge gave Coloplast permission to appeal (findings of obviousness can only be overturned on appeal if the trial judge has made an error of law or erroneous finding of fact), so further developments should be monitored. Salts had sought a stay of these proceedings pending the outcome of the EPO proceedings but this had been declined, with the Court concluding that some commercial certainty would be achieved at a considerably earlier date in the UK proceedings, which represents one of the largest markets for Coloplast and the largest market for Salts.

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