Should we have seen it coming?
There are a number of important aspects to the Supreme Court decision in Actavis v Eli Lilly1, but the most surprising, and indeed radical, was undoubtedly the advent in English law of a doctrine of equivalents.
The possibility that courts might consider the prosecution history of a patent has been discussed on and off over the years. Indeed, Arnold J’s judgment in the first instance case appeared to open the door, at least a little, to some form of (the arguably linked) “file wrapper” estoppel. However, the continual rebuttal of the existence of a doctrine of equivalents in English law had been one of the most consistent aspects of the jurisprudence, certainly over the last 20 years. With this, apparently, was a rebuttal of any need for a form of file wrapper or “prosecution history” estoppel.
