Kirin-Amgen Inc v Hoechst Marion Roussel Ltd
[2004] UKHL 46
Ratio Decidendi
Patent claims should be interpreted purposively — ascertaining what a person skilled in the art would have understood the patentee to have used the language of the claim to mean. The Protocol on Interpretation of Article 69 EPC requires a position between strict literal and broad purposive construction.
Facts
A dispute over the scope of a patent for erythropoietin (EPO) produced by recombinant DNA technology.
Judgment Summary
Lord Hoffmann reformulated the approach to patent interpretation, holding that the question is always what the skilled person would have understood the patentee to mean by the language used in the claim.
Key Quotes
"The question is always what the person skilled in the art would have understood the patentee to be using the language of the claim to mean."
— Lord Hoffmann
Subsequent Treatment
Leading authority on patent claim interpretation, though aspects were refined in Actavis v Eli Lilly [2017] UKSC 48.