A new bag of tricks? Obvious if it could have been done before (says the Patents Court)

Written on 1 Feb 2021

In order to establish obviousness for the purposes of a patent application, it is enough to show that the idea said to be the invention would have occurred to the skilled person. It is not necessary to show that the skilled person would have actually implemented the idea – or in other words, whether they would have been motivated to actually make the invention.

On 18 January 2021, Mr Nicholas Caddick Q.C (sitting as a Deputy High Court Judge) ruled that Coloplast A/C's patent was invalid on grounds of obviousness. The decision can be seen as a major success for the defendant, Salts Healthcare, which had earlier been denied in its application to stay the UK action pending the outcome of parallel EPO opposition proceedings (The EPO has held the Patent to be invalid for lack of novelty, but the decision is currently under appeal and is based on a different claim set and evidence to that before the English court).

What was the dispute about?

Coloplast initiated infringement proceedings against Salts in relation to Salts' range of ostomy bags. Ostomy bags are small, waterproof pouches that attach to an opening in the human body, known as a stoma, to collect waste. Ostomy bags are typically made of two layers of barrier film (which form the collecting pouch) and an additional layer, known as the comfort layer, which acts as an extra barrier between the user and the collecting pouch.

Comfort layers can be removable (non-integrated) or non-removable (integrated to the collecting pouch). As of the priority date, the judge concluded that the only available integrated comfort layers were made of non-woven materials.

Coloplast's invention claimed a new collecting bag (an ostomy bag with accompanying comfort layer) incorporating a partially woven textile material. It was claimed that this new 'woven' bag would have a significantly higher resistance to external forces, improved visual and tactile characteristics and have greater resistance to "snagging and pilling" when compared with conventional bags.


Salts argued that the Coloplast's patent was invalid for a number of reasons, including because the claims were obvious having regard to the common general knowledge and five items of prior art. In assessing obviousness, the judge applied the well-known approach of Windsurfing/Pozzoli.

The judge concluded that the inventive concept relied on by Coloplast and accepted by the court – the use of woven material to make an integrated comfort layer with improved properties – was not inventive. The reasons why woven materials had not been previously used were commercial rather than technical: it was common knowledge that the use of woven material for an integrated comfort layer was possible but this concept had not been pursued because of its higher costs and environmental concerns, as the use of wovens typically involved a larger quanitity of plastic. The court dismissed the alleged technical advantages of the claimed invention as factors the skilled person would have been well aware of.

In reaching this conclusion, the judge noted that the fact that an idea had not previously been implemented, or that there had been an unexplained delay in adopting an idea, should not in itself be mistaken as proof of inventiveness. As the courts have previously pointed out, there may be a number of non-inventive reasons why a particular allegedly inventive step had not been taken. These could include commercial constraints or the adequacy of existing products. There may be little incentive to modify an existing highly successful and satisfactory product.

When considering whether the relevant technical step requires a degree of inventiveness, one must focus on whether the step adds something new to the existing stock of knowledge. This addition might be the idea of using an existing technique to do something which no-one had previously thought of doing, or it might involve finding a way to do something which nobody had previously been able to do.

In this instance, the skilled person, subject to minor adjustments, would have been able to use the same commonly known techniques used to weld a non-woven comfort layer as was required to weld an integrated woven comfort layer. As of the priority date, the skilled person would have been well aware that it was possible to create an integrated woven bag, they just had no desire to do so.

Osborne Clarke comment

This decision serves as a reminder to patentees not to be seduced into making arguments that relate to commercial matters. The critical question when determining obviousness is whether the relevant step requires a degree of invention. This is to be determined by assessing whether the relevant step adds something new to the existing stock of knowledge.

The judgment also contains some useful commentary on the role of experts, reiterating that their role is to educate the court on the technology in question rather than to provide their opinion on the relevant legal tests. In this case, while Coloplast's expert didn't have the attributes of the skilled person, the court concluded that her evidence was helpful. Legal advisers should remember that while it is often beneficial to appoint experts akin to the skilled person an expert with different qualities will not be precluded from giving useful evidence, so long as it is in regard to a technical matter that is relevant to the case.