The replacement of the doctrine of pith and marrow by the catnic test in English Patent Law : a historical evaluation

Abstract

This dissertation is a historical evaluation of the movement of the English courts from the doctrine of pith and marrow to the Catnic test in the determination of non-textual infringement of patents. It considers how and why the doctrine was replaced with the Catnic test. It concludes that this movement occurred as a result of the adoption by a group of judges of literalism in the construction of patents while another group dissented and maintained the correct application of the doctrine. Although the Court of Appeal and the House of Lords initially approved the literalist approach, they, after realising its untennability, adopted the dissenters’ approach, but, ultimately, adopted the Catnic test in which features of the dissenters’ approach were included. The dissertation concludes that the doctrine of pith and marrow, correctly applied, should have been retained as the Catnic test creates uncertainty and confusion.