James Mellor QC and Charlotte May recently appeared for the Claimant and Third Parties (together ‘Smith & Nephew’) in patent proceedings regarding a European patent owned by Convatec.
Convatec’s patent concerns a method of silverisation of gel-forming fibres used in wound dressings, using a sodium chloride reagent present at a concentration between 1% and 25% of the total volume of treatment. Smith & Nephew sought a declaration of non-infringement for their own method of siverisation, which used sodium chloride at a concentration of 0.77%.
Giving judgment, Birss J observed that that the “significant figures” approach to deciding whether a given figure was within a range claimed in patent, was one that had been applied in many earlier cases by the courts in England and the EPO Boards of Appeal. He held that in the present case that approach would be the natural one for the skilled person to take, construing the claim to cover a sodium chloride reagent of 0.95% or above. Accordingly Smith and Nephew’s method did not infringe.
It was further held that four of Smith and Nephew’s experiments, conducted in the course of gaining regulatory approval for their wound dressing, which had used sodium chloride concentrations above 0.95% had infringed the patent on that construction. However, springboard relief was not appropriate in all the circumstances. In so holding, Birss J summarised the relevant factors in considering final springboard relief in a patent cases in a 5-point list (see paragraph 133 of the judgment).