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"Formstein defence" available to defeat patent infringement claim in case concerning disposable washbowls

Posted on 28 October 2022

Nicholas Caddick KC (sitting as a Deputy High Court Judge in the Intellectual Property Enterprise Court) handed down his decision in Vernacare Limited v Moulded Fibre Products Limited (MFP) in August. The judgment is of particular interest as it is the first time that the 'Formstein' defence has been determinative in UK patent infringement proceedings. Vernacare Limited alleged that its competitor, MFP, had infringed two of its patents GB 2446793 (the “793 Patent”) and GB 2439947 (the “947 Patent”). The 793 Patent relates to the shape of, and the 947 Patent the composition of, disposable moulded paper pulp washbowls, intended for use by staff in the medical sector to clean patients confined to their beds hygienically. 

When assessing the claim to infringement on the basis of the doctrine of equivalence, the Court applied the Formstein defence, established under German law – this provides that where a product is found to infringe by the doctrine of equivalence, but is also found to be obvious over the prior art, the relevant claim of the patent will be found valid, but not infringed. The defence had previously been considered by the UK courts in Facebook v Voxer and in the earlier case of Technetix v Teleste. In the Facebook v Voxer case, Birss LJ had provided obiter guidance as to the availability of the defence and how it should operate. This guidance has now been applied by the Court in this case.

The decision also contains interesting analysis on the characterisation of the skilled person, and on arguments of long felt need and commercial success as indications of inventive step. 

The 793 Patent and the Formstein defence

The 793 Patent provides a shape for a disposable bowl made from paper pulp which can be lifted easily whilst holding a considerable volume of liquid without fear of disintegration. Previously existing paper pulp disposable bowls, used by hospitals as bed pans, were designed to hold smaller volumes of liquid and were not suitable for use as washbowls as they had insufficient strength and would likely rupture if lifted by the rim. The solution provided by the 793 Patent was to include "recesses" with near vertical sides, which were to be used to aid lifting the bowl, as these provided a more rigid structure.

MFP denied that its washbowl fell within the claims of the 793 Patent. The Court agreed that its washbowl did not, on a "normal" construction, infringe the 793 Patent, as it had a single ridge rather than multiple recesses; it also did not have near vertical sides.

However, the judge also considered whether MFP's washbowl infringed the 793 Patent on the basis of equivalence, applying the approach set out in Actavis v Eli Lilly. He concluded that MFP had not infringed on this basis either. This was because, in answering the third question in Actavis v Lilly, the skilled person would have concluded that the patentee intended that a strict compliance with the literal meaning of the relevant claim was an essential requirement of the invention.

Also, MFP could rely on the Formstein defence, as explained by Birss LJ in Facebook v Voxer. The variant, namely the strengthening rib around the side walls of the washbowl, was not inventive but was part of the common general knowledge. Applying the Formstein defence, the judge determined that where an equivalent device lacks novelty or is obvious, the claim scope must be confined to its normal construction, so the claim remains valid but not infringed. Accordingly, whilst the 793 Patent was valid, none of its claims were infringed by MFP's washbowl.

The skilled person

The relevant “art” was the making of moulded paper pulp products. Vernacare argued that the skilled person would have an understanding of moulding techniques needed to achieve particular shapes, but would not have a particularly broad chemistry background. It said that the skilled person would have a working knowledge of the ingredients typically used to make moulded paper pulp products but, if a technical issue arose regarding pulp formulation, they would seek specialist advice. MFP accepted this characterisation of the skilled person in relation to the 793 Patent but argued that the skilled person for the 947 Patent differed and would include a “Skilled Paper Chemist” with a chemistry or process engineering degree who would either be employed or would routinely be consulted on matters of pulp composition.

The judge agreed with Vernacare's characterisation of the skilled person. MFP's characterisation would result in the skilled person having a much greater knowledge of "wet end" chemistry than would have been the case in the real world. It was common for moulded paper pulp manufacturers to seek specialist external advice, but this did not make such an external adviser part of the skilled person within the art of the moulded paper pulp sector.

947 Patent and long felt want and commercial success arguments

The 947 Patent concerns the composition of the moulded paper pulp washbowl. The inventive concept was that a detergent resistant washbowl could be made by adding a fluorocarbon to the pulp mix. MFP's washbowl fell within the relevant claims of the 947 Patent (and therefore infringed) but it argued that the 947 Patent was invalid for being obvious over two Japanese patent applications that included the use of fluorocarbons to make pulp food containers resistant to oil and water.

Vernacare relied upon arguments of long felt want and commercial success as secondary indications that the 947 Patent was not obvious. As the judge concluded that nothing in the prior art would have made it obvious to the skilled person to add a fluorocarbon to the pulp mixture of a disposable paper pulp washbowl, he did not need to consider these arguments but did provide obiter commentary.

In relation to long felt want, moulded paper pulp products had been introduced in the 1960s for use in the care sector, but were not detergent resistant. Producing a detergent resistant variant for use as a washbowl was the problem the 947 Patent addressed. The judge was not convinced that the lack of a detergent resistant washbowl was seen as a significant problem as at 2006, the filing date of both patents. He was critical of Vernacare's limited evidence in support of its argument that there was a need for disposable washbowls to limit infection. There was also no documentary evidence to support a long felt want.

As for commercial success, whilst Vernacare's UK sales figures were "healthy", the profit margin and the size of the market overall were not clear. The sales figures could be reflective of the success of Vernacare's "very effective marketing team" rather than of the originality of the invention. Although obiter, this provides useful guidance on the approach to arguments of commercial success.

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