Supreme Court of the United Kingdom – Anonymised Case Summary
Factual and Procedural Background
Company A owned a granted European patent (“the 181 patent”) covering the use of the compound tadalafil in very low oral doses (1–5 mg, maximum 5 mg per day) for the treatment of sexual dysfunction. Company B, a consortium of generic manufacturers, brought revocation proceedings alleging (among other grounds) lack of inventive step.
At first instance, Judge Birss found that while it was obvious to investigate tadalafil generally, the specific 5 mg daily dose was not obvious and therefore upheld the patent. The Court of Appeal (Judges Kitchin, Floyd and Lewison) reversed that decision and held claims 1, 7 and 10 obvious. Company A appealed to the Supreme Court. Judge Hodge, giving the unanimous judgment of a five-judge panel, dismissed the appeal and restored the Court of Appeal’s order.
Legal Issues Presented
- Whether, in light of section 3 of the Patents Act 1977, the claimed low-dose tadalafil regimen involved an inventive step or was obvious to the notional skilled team at the priority date.
- Whether the Court of Appeal was entitled to overturn the trial judge’s evaluative conclusion on obviousness.
Arguments of the Parties
Appellant (Company A)
- The invention lay in discovering that 1–5 mg daily tadalafil was efficacious with minimal side-effects, enabling convenient once-daily dosing—something not suggested in prior art.
- At the priority date there was no reason to test as low as 5 mg; success at that dose was unpredictable, so testing it was not “obvious to try”.
- The Court of Appeal wrongly focused on the process (routine trials) rather than the claimed subject-matter, contrary to both section 3 and the European Patent Office’s problem-and-solution approach.
- The cost, complexity and unpredictability of clinical trials justified patent protection even where the work was “routine”.
Respondents (Company B)
- Given the earlier “Daugan” patent disclosing tadalafil for erectile dysfunction, it was routine for the skilled team to conduct Phase IIb dose-ranging studies that would inevitably include 5 mg and reveal its efficacy.
- Each research step (pre-clinical, Phase I, Phase IIa, Phase IIb) was standard; no inventive insight was required.
- An unexpected bonus effect (fewer side-effects) does not render an otherwise obvious dosage inventive (Hallen v Brabantia principle).
- The trial judge over-emphasised purported “value judgments”; the evidence showed the team was “very likely” to test 5 mg once the therapeutic plateau was discovered.
Table of Precedents Cited
| Precedent | Rule or Principle Cited For | Application by the Court |
|---|
| Windsurfing / Pozzoli test (Pozzoli SPA v BDMO SA) | Structured four-step framework for assessing obviousness in UK law. | Used to analyse the parties’ submissions and highlight the statutory focus on step (4). |
| Actavis v Merck [2009] 1 WLR 1186 | Dosage patents are in principle patentable, but most dosage regimens will be obvious because dose-ranging studies are routine. | Relied on to illustrate why a court must examine whether the regimen truly departs from routine expectation. |
| Conor v Angiotech [2008] UKHL 49 | Obviousness must be judged against the specific claim, avoiding hindsight; “obvious to try” requires a reasonable prospect of success. | Quoted to confirm that the skilled team’s real-world expectations are central, but here those expectations included running further low-dose studies. |
| Generics v Lundbeck [2007] RPC 32 & [2009] UKHL 12 | Non-exhaustive list of factors relevant to obviousness (motive, alternatives, effort, expectation, surprise). | Both courts used these factors; disagreement lay in how they were weighed. |
| Hallen & Co v Brabantia [1991] RPC 195 | “Bonus effect” doctrine – an extra advantage does not rescue an otherwise obvious invention. | Supreme Court treated reduced side-effects at 5 mg as a mere bonus. |
| Technograph [1972] RPC 346 | Warning against step-by-step hindsight analysis. | Accepted, but held inapplicable because the skilled team’s testing sequence was foreseeable without hindsight. |
| Synthon v SKB [2005] UKHL 59 | Distinction between disclosure and enablement; a valid patent must provide both. | Used to show that the earlier Daugan patent must already enable tadalafil treatment, so the skilled person’s task was merely optimisation. |
| Biogen v Medeva [1997] RPC 1 | Appellate courts should be slow to overturn a trial judge’s evaluative conclusions absent error of principle. | Supreme Court identified such an error and upheld the Court of Appeal’s intervention. |
| EPO case T 939/92 (Agrevo/Triazoles) | Patent monopoly must correspond to the technical contribution; formulating the “objective technical problem”. | Cited to align UK law with EPO principles on obviousness and dosage patents. |
| EPO Enlarged Board G 2/08 (Abbott Respiratory/Dosage Regime) | Novel and inventive dosage claims are in principle patentable under EPC. | Confirmed that no relaxation of obviousness applies merely because the claim concerns dosage. |
Court's Reasoning and Analysis
Judge Hodge began by reaffirming the “patent bargain”: monopoly is justified only by genuine technical contribution. The central prior art (the “Daugan” patent) already taught tadalafil for erectile dysfunction. Implementing that teaching necessarily required routine dose-finding studies.
The trial judge had found that, after an initial study revealed a therapeutic plateau at 25–100 mg, the skilled team would be “very likely” to run a further Phase IIb study including 5 mg and 10 mg doses. Both experts agreed such follow-up was a “no-brainer.” The Supreme Court held that the judge erred in giving decisive weight to:
- The lower numerical size of 5 mg compared with earlier doses;
- Lack of an ex ante prediction of efficacy at 5 mg;
- The element of surprise when reduced side-effects emerged; and
- Alleged “value judgments” after discovering the plateau.
Once the judge’s own factual finding—that the skilled team would probably test 5 mg—was given proper primacy, the conclusion of obviousness was inescapable. The added benefit of fewer side-effects was characterised, applying Hallen, as a “bonus effect” that could not confer inventiveness.
Because this mis-weighting amounted to an evaluative error of principle, the Court of Appeal was entitled to substitute its own assessment; the Supreme Court agreed with that substitution.
Holding and Implications
APPEAL DISMISSED – CLAIMS 1, 7 AND 10 INVALID FOR LACK OF INVENTIVE STEP.
Immediate effect: Company A’s low-dose tadalafil claims are revoked in the United Kingdom, enabling Company B and other generic manufacturers to market competing products.
Broader implications: The judgment clarifies that, for dosage patents, carrying routine pre-clinical and clinical trials to their logical end can render a claimed regimen obvious, even if unexpected benefits arise. Courts must analyse all factual factors, but where the skilled team would predictably conduct the key experiment, a later-identified low dose will seldom clear the inventive-step hurdle.