Failure of embodiments disclosed but not claimed to aid claim scope before the UK courts

Need for description amendment to align the description with allowed claims remains a much discussed EPO requirement (Guidelines for Examination in the EPO, Part F-IV-17 4.3). It has been the case that some EPO examiners will permit retention in the description of embodiments not explicitly claimed provided they are distinguished from ‘embodiments of the invention’ by reference to ‘embodiments of the disclosure’. A recent medical device case before the UK Intellectual Property Enterprise Court (Well Lead Medical V C J Medical; for the full judgment see here) illustrates that such manner of amendment cannot be relied upon however to aid broadening of claim language when it comes to considering infringement.

The patent of note (EP3760143B) concerned a device for fragmenting stones in a patient and withdrawing the fragments using suction. Well Lead and C J Medical were competitors in marketing devices of this type for removing kidney stones. The case for infringement brought by Well Mead focussed on the manner of removal of the resulting kidney stone fragments via a device part, more specifically reference in claim 1 to a sheath lumen and side arm lumen having the same diameter. The description retained reference to variation of the relevant lumen diameters as much as 20% while stating: “One important feature of the current invention is a sheath 20 that has a side arm 50 that has an identical or nearly identical luminal circumference.” In the same paragraph, reasoning was also presented for this choice being favourable.

The judge took the view that the words “the same” in claim1 would be seen by the skilled reader as meaning the same within manufacturing tolerance, taken to be ± 5%. Claim 1 was held to lack inventive step but on normal claim interpretation C J Medical’s ‘Seplou Sheath’ was thereby held to infringe claim 3 only in so far as it was supplied as a single product size out of five different sizes under S 60(2) of the UK Patents Act. In moving moved on to consideration of infringement by equivalents, further broadening of the scope of the relevant claim language was held by the judge to fail by answer ‘yes’ to the final question of the three questions set by the UK Supreme Court Decision of Actavis v Lilly: Would the skilled reader of the patent have concluded that the patentee intended strict compliance with the literal meaning of the relevant claims of the patent was an essential requirement of the invention. The judge saw no reason to see disclosed but unclaimed embodiments in the description as having any value in considering the scope of clear claim language. The principle of ‘disclosed but not claimed’ as noted by the judge was previously raised in the context of the pharma case Akebia Therapeutics v Fibrinogen [2020] EWHC but its application even in a simple device case is now shown.

Practice point

Retaining reference to embodiments in the description which are not strictly within the language of the allowed claims by for example changing ‘embodiment of the invention’ to ‘embodiment of the disclosure’ can be convenient in amending the description of a European patent ahead of issue of the Notice of Intention to Grant with a view to saving time and cost. However, retaining reference to such embodiments in this manner cannot be relied upon to aid argument for extending claim scope.

A more detailed report on the decision will appear in the CIPA journal.