Smith & Nephew plc v Convatec Technologies Inc, 14 December 2012, Case No. A3/2012/1456, Neutral Citation Number:  EWCA Civ 1638
HHJ Birss QC held Convatec’s patent claiming a way of making moist wound dressings containing ionic silver in a light stable form to be sufficient and inventive. Smith & Nephew appealed the finding of inventive step over Kriedl, a US patent published in 1946, which disclosed a method for making silver halide preparations with an excess of halide to bring about light stability. The appeal was dismissed.
The key issue which had been before Judge Birss was whether it was obvious to apply the teaching of Kreidl to new materials such as Aquacel, a gel forming fibre, which formed part of the common general knowledge by the priority date. The Judge had held that the skilled person would consider whether to test Aquacel in Kreidl’s conditions but would have no certainty that the test would work due to the existence of alternative explanations for Kreidl’s results (namely adsorption, which was the theory set out in Kriedl or physical shielding, a theory suggested by Convatec’s expert).