Synthon BV v. Smithkline Beecham plc

The House of Lords held that anticipation under section 2(3) of the Patents Act 1977 requires both prior disclosure of subject-matter which, if performed, would necessarily infringe the later patent and sufficient enablement to permit the skilled person to perform that disclosed subject-matter. The court emphasised that disclosure and enablement are distinct requirements.

Applying those principles, the court found that Synthon's earlier patent application disclosed crystalline paroxetine methanesulfonate (PMS) and, on the judge's findings of fact (including that PMS was monomorphic), a skilled person using the application together with common general knowledge would have been able to obtain the crystalline form claimed by SmithKline Beecham. An erroneous IR spectrum in the earlier application was immaterial where the crystalline product was in fact monomorphic.

The appellants (Synthon) and the respondents (SmithKline Beecham plc) each discovered an improved paroxetine salt (paroxetine methanesulfonate, PMS). Synthon filed an earlier international patent application disclosing PMS, including an example (Example 1) describing preparation of crystals and stating characteristic analytical data. SmithKline obtained a patent claiming a particular crystalline form of PMS identified by IR and XRD peaks. Synthon sought revocation of SmithKline's patent on the ground that the crystalline form claimed was anticipated by Synthon's earlier application under section 2(3) of the Patents Act 1977.

Nature of the claim: revocation of a patent for lack of novelty (anticipation) by matter in an earlier patent application published under section 2(3).

Issues before the court:

• whether the Synthon application disclosed the invention claimed by SmithKline (disclosure); and
• whether the disclosure was sufficiently enabling for the skilled person to perform the invention (enablement).

At first instance Jacob J found that Synthon's application both disclosed crystalline PMS and enabled the skilled person to make it; he concluded SmithKline's patent lacked novelty. The Court of Appeal reversed, treating the example and the differing IR data as significant and concluding the earlier application did not make available the claimed crystalline form. The House of Lords allowed Synthon's appeal and restored Jacob J's decision.

Reasoning: the House of Lords reiterated established authorities (for example Hill v Evans and General Tire) that anticipation requires prior disclosure of subject-matter which, if performed, would necessarily infringe the later patent. It also reaffirmed that enablement is required and that the tests for enablement apply to state-of-the-art material deemed prior art under section 2(3). On the facts the court accepted the judge's findings that (i) PMS crystals were monomorphic so the IR discrepancy in Synthon's example was not determinative, (ii) the Synthon application disclosed crystalline PMS of 98% purity and its advantages, and (iii) a skilled chemist, using the disclosure together with common general knowledge and routine trial and error, would have been able to produce crystalline PMS within a reasonable time. The combination of disclosure and enablement meant the earlier application anticipated the SmithKline claim.

Appeal allowed. The House of Lords restored the decision of Jacob J revoking the SmithKline patent. The Lords held that Synthon's earlier application both disclosed crystalline paroxetine methanesulfonate and, on the judge's factual findings (including monomorphism), enabled the skilled person to make the crystalline form claimed; an erroneous IR reading in the earlier application did not prevent anticipation where the product was in fact a single crystalline form.