Construing patents: pretend the defendant had never been born

Convatec Ltd. & Ors v Smith & Nephew Healthcare Ltd & Ors [2011] EWHC 2039 (Pat) (27 July 2011) is a 185-paragraph blockbuster of a judgment of HHJ Birss QC, sitting in the Patents Court for a change. The case itself is a fairly straightforward infringement claim and invalidity counterclaim concerning wound dressings made from cellulose in various forms. There is a lot of consideration of wound dressing techniques and the construction of the claims of the claimants' patent - leading the judge to point out, as the IPKat notes, that it will not do to try to read the claims onto the defendant's product: "A patent is to be construed as if the infringer had never been born." (Nobel's Explosives Co. v Anderson (1894) 11 RPC 519.) Remarkably, Floyd J cited exactly the same principle (indirectly, given that he was quoting from Jacob LJ's judgment in Technip France's Patent [2004] RPC 46) in his judgment in Cephalon v Orchid & Mylan [2011] EWHC 1591 (Pat):

It is clear that one does not start with the alleged infringement, read the patent, and ask whether the patentee meant to cover it. But it is sometimes necessary to have regard to the infringement in order to identify the question which has to be asked on construction. In Technip France's Patent [2004] RPC 46 Jacob LJ put it in this way:

"Although it has often been said that the question of construction does not depend on the alleged infringement ("as if we had to construe it before the defendant was born") per Lord Esher M.R. in Nobel's Explosives Co. v Anderson (1894) 11 R.P.C. 519 at 523), questions of construction seldom arise in the abstract. That is why most sensible discussions of the meaning of language run on the general lines "does it mean this, or that, or the other?" Rather than the open-ended "what does it mean?"

I wonder whether I can encourage people to adopt the title "Man of the World Rule" for this principle - after the bleak but beautiful song by Peter Green?