Synthon BV v SmithKline Beecham plc

Reference: [2005] UKHL 59; [2006] 1 All ER 685; [2006] RPC 10; (2005) 86 BMLR 130

Court: House of Lords

Judge: Lord Bingham of Cornhill, Lord Hoffmann, Lord Walker of Gestingthorpe, Baroness Hale of Richmond, Lord Brown of Eaton-under-Heywood

Date of judgment: 20 Oct 2005

Summary: Patents – Enabling disclosure – Novelty – State of the art – Patent invalid by reason of prior disclosure which, if performed, would infringe the patent – Anti-depressants – Crystalline form – Patents Act 1977, ss. 1, 2, 3, 5 and 14

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Instructing Solicitors: Bird & Bird for the Appellant; Simmons & Simmons for the Respondent


The case is about Paroxetine, a compound used to treat depression and related disorders. It had for some time been marketed in the form of its hydrochloride hemihydrate salt under the name Paxil or Seroxat. The proceedings arose out of the more or less simultaneous discovery in about 1997 by the appellants Synthon BV, a Dutch pharmaceutical company, and the respondents, Smithkline Beecham plc (“SB”), a UK pharmaceutical company, that a different paroxetine salt, paroxetine methanesulfonate (“PMS”), had properties which made it more suitable for pharmaceutical use. It was more stable, less hygroscopic and much more soluble, so that it could be prepared in higher concentrations. After Synthon had filed its application but before it was published, SB filed a document dated 6 October 1998 which gave it priority for a UK patent application filed on 23 April 1999. The patent was published on 10 May 2000. On 7 March 2001 Synthon commenced proceedings to have the SB patent revoked.


The case explains how it comes about that the “state of the art” involves both disclosure and enablement.


Allowing the Appeal and restoring the Orders of Jacob J., Lord Walker gives a clear explanation of how it comes about that the “state of the art” involves both disclosure and enablement. The composite expression “enabling disclosure” (which originated in the United States of America) has been in frequent use in this country for at least fifteen years. One of the first reported instances may be found in the judgment of Falconer J in Genetech Inc’s (Human Growth Hormone) Patent [1989] RPC 613. This passage was referred to and approved by Lord Oliver in Asahi Kasei Kogyo KK’s Application [1991] RPC 485, 539. The most relevant provisions of the Patents Act 1977 are ss. 1, 2, 3, 5 and 14. One of the issues which arose in the past was how far enabling disclosure was to be regarded as implicitly required in statutory provisions expressed in different terms from s.14, that is in the concept of the state of the art, which is of central importance to s.2.


Lord Walker warns that the expression ‘enabling disclosure’ must be handled with some care. The practical importance of keeping the two requirements distinct will vary with the factual situation. In the case of a low-tech invention (for instance a simple agricultural machine such as the hay rake with ground driven wheels in Van der Lely) the simple disclosure of the invention will probably be enough to enable the skilled person to perform it. By contrast in the case of a high-tech invention in the field of pharmaceutical science the bald assertion of the existence of the invention may have to be accompanied by detailed disclosure enabling the skilled person to perform it. But in testing the adequacy of the enablement it may be assumed that the skilled person will have to use his skill, and may have to learn by his mistakes (see Lord Reid’s reference to “trial and error” in Van der Lely [1963] RPC 61,71).