Merrell Dow v Norton

A product lacks novelty where prior information enables the skilled public to perform a process which inevitably makes that product, even though its chemical identity was then unknown. The product need only have been disclosed under a description sufficient to work the claimed invention in the relevant manner.

Mere prior use does not anticipate an invention under the Patents Act 1977 unless it communicates the necessary enabling information. Secret or uninformative acts may therefore infringe a later patent without having anticipated it. For a product claim, however, novelty must extend throughout the monopoly: if any claimed method of manufacture or form of the product belongs to the state of the art, the claim lacks novelty to that extent.

Merrell Dow held a patent containing a product claim for the acid metabolite produced when the antihistamine terfenadine is metabolised in the human liver. After the earlier terfenadine patent expired, it brought two infringement actions against pharmaceutical companies supplying terfenadine.

Aldous J struck out the actions because, so far as the metabolite claim covered manufacture in the human body following ingestion of terfenadine, the claimed invention was not new. The Court of Appeal affirmed that decision. The central issue before the House was whether earlier clinical use or the published terfenadine specification had made that manner of producing the metabolite part of the state of the art under sections 1 and 2 of the Patents Act 1977.

1. The appeals were dismissed unanimously. Lord Hoffmann delivered the only substantive speech. Lord Jauncey of Tullichettle, Lord Browne-Wilkinson, Lord Mustill and Lord Lloyd of Berwick agreed with his reasons. The Court of Appeal's order was affirmed, and the appellants were ordered to pay the respondents' costs.

2. Per Lord Hoffmann, section 2 of the Patents Act 1977 must, so far as possible, have the same effect as article 54 of the European Patent Convention. Decisions of the European Patent Office are not strictly binding on United Kingdom courts, but carry great persuasive authority because of the Boards' expertise and the desirability of consistent interpretation.

3. A product claim confers protection over the product wherever it exists and however it is made. Its novelty must be co-extensive with that monopoly. Claim 24 therefore covered the metabolite made in the liver as well as metabolite made synthetically or in isolation. If any claimed method or form was part of the state of the art, the invention lacked novelty to that extent.

4. The clinical trials did not anticipate the invention merely because volunteers had unknowingly made the metabolite. Under section 2(2), matter enters the state of the art only through the communication of information. The Patents Act 1977 therefore qualified the former rule under which secret or uninformative use could destroy novelty. Subject to section 64, an earlier secret or uninformative act may fail to anticipate even though the same act would infringe a later patent.

5. The published terfenadine specification did anticipate the claimed manufacture of the metabolite in the body. It taught the skilled public how to make and ingest terfenadine for its antihistamine effect, with the inevitable consequence that the metabolite was produced. A product need not have been known by its chemical composition. It is enough that the prior disclosure made it known under a description sufficient to work the claimed invention in the relevant manner.

6. Whether a person works a product invention is an objective question independent of that person's knowledge. The position may differ for a claim to a particular use of a product, where the patented purpose may form part of the invention. The metabolite's chemical identity had remained unknown, but the earlier specification contained enough information to enable its production in the body. The patent was therefore invalid to the extent challenged.

1. House of Lords: The appeals were dismissed unanimously. The Court of Appeal's order of 16 February 1994 was affirmed.

2. Court of Appeal: Affirmed Aldous J's dismissal of the infringement actions on the ground that the relevant product claim lacked novelty.

3. High Court: Aldous J dismissed the actions under RSC Order 14A. He ordered revocation of the patent but stayed that order pending an application to amend the specification.