It has been feature of our (and no doubt every other country's patent law) since the Statute of Monopolies that a patent monopoly should be granted only for an invention that is new. S. 2 (1) of the Patents Act 1977 provides that an invention shall be taken to be new only if it does not form part of the state of the art. Now the interesting point of this case is that the "state of the art" can be either
"all matter (whether a product, a process, information about either, or anything else) which has at any time before the priority date of that invention been made available to the public (whether in the United Kingdom or elsewhere) by written or oral description, by use or in any other way"
"matter contained in an application for another patent which was published on or after the priority date of that invention, if the following conditions are satisfied, that is to say—This case was about the second of those provisions, that is to say matter in an application for a patent that was published on or after the priority date.
(a) that matter was contained in the application for that other patent both as filed and
as published; and
(b) the priority date of that matter is earlier than that of the invention."
The parties discovered that the paroxetine salt, paroxetine methanesulfonate ("PMS"), has properties which make it more suitable for pharmaceutical use at approximately the same time. Synthon BV ("Synthon") applied for an international patent for a broad class of sulphonic acid salts including PMS on 10 June 1997 which was published on 17 Dec 1998. SmithKline Beecham Plc ("SKB") filed an application on 6 Oct 1998 that gave priority for a UK patent application filed on 23 April 1999 which was published on 10 May 2000. As it was by them clear that PMS was one of many paroxetine salts suitable for a particular method of treatment, SKB narrowed its claim to a particular form of crystalline PMS.
Synthon applied to revoke SKB's application on the ground of lack of novelty, but as the matter upon which it relied was not known until after 6 Oct 1998 it had to rely on matter contained in its own patent application. That, of course, was conditional upon its application disclosing the invention and upon an ordinary skilled man being able to perform the invention using only the disclosed matter and common general knowledge.
Unfortunately for Synthon, their specification did not actually disclose how to make the preparation in the required form because it used the wrong solvent. They argued, however, that the skilled man could easily find another and that he would end up making the patented invention. At trial, Mr Justice Jacob (as he then was) bought that argument.
The Court of Appeal reversed Mr Justice Jacob but the House of Lords (or at least Lord Hoffmann) did not appear to be quite sure why. As noted above, anticipation is conditional upon disclosure of the invention and the ability of the skilled addressee to perform it. Lord Hoffmann surmised that the Court of Appeal must have got the two concepts mixed up which is easily done as they are very close when considered together. He surmised that the Court of Appeal either did not consider that Synthon's invention had anticipated SKB's in which case it was wrong or that it did not think that a skilled man would be able to make the invention in which case it was straying from its appellate role.
Points to note in this case are paragraphs 19 to 33 of Lord Hoffmann's speech in which he discusses the two conditions that he called "disclosure" and "enablement" and paragraphs 57 to 64 of Lord Walker's on the background and policy to s.2 of the Patents Act 1977.