Catnic Components Ltd v Hill & Smith Ltd
Patent claims must be given a purposive construction, asking whether persons skilled in the art would understand that strict compliance with a particular word was intended to be essential.
Facts
Catnic held a patent for a steel lintel, used to support the brickwork above doors and windows, which had a rear member extending vertically. Hill & Smith made a similar lintel, in which the rear member was inclined at a few degrees from the vertical, which made little practical difference to its strength. Hill & Smith argued that its lintel did not infringe the patent, because its rear member was not vertical, as the claim required.
Legal principle
The House of Lords held that Hill & Smith had infringed the patent. Lord Diplock said that a patent specification should be given a purposive construction rather than a purely literal one, and that the question is whether persons with practical knowledge and experience of the kind of work in which the invention was intended to be used would understand that strict compliance with a particular descriptive word or phrase appearing in a claim was intended by the patentee to be an essential requirement of the invention. A skilled person would not have understood the word vertical to exclude a lintel inclined at a few degrees, which worked in the same way.
Related cases on patents: claim construction and infringement
- Actavis UK Ltd v Eli Lilly & Co [2017] UKSC 48
- Gillette Safety Razor Co v Anglo-American Trading Co Ltd (1913) 30 RPC 465
- Grimme Maschinenfabrik GmbH & Co KG v Scott [2010] EWCA Civ 1110, [2011] FSR 7
- Improver Corp v Remington Consumer Products Ltd [1990] FSR 181
- Kirin-Amgen Inc v Hoechst Marion Roussel Ltd [2004] UKHL 46, [2005] RPC 9
- Monsanto Technology LLC v Cefetra BV Case C-428/08, [2010] ECR I-6765
- Schütz (UK) Ltd v Werit (UK) Ltd [2013] UKSC 16, [2013] RPC 16
- Smith Kline & French Laboratories Ltd v Evans Medical Ltd [1989] FSR 513
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