Factual and Procedural Background
Company B is the proprietor of European Patent (UK) No 1 313 508 and its corresponding French, Italian and Spanish designations. The patent discloses that the anticancer agent “pemetrexed disodium” can be administered safely when combined with vitamin B12 (with optional folic acid), thereby avoiding previously fatal side-effects. Company B has marketed the medicament under the brand name “Alimta” since 2004.
Company A proposed to market three competing products which, when ultimately administered with vitamin B12, would employ (a) pemetrexed diacid, (b) pemetrexed ditromethamine or (c) pemetrexed dipotassium rather than the patented pemetrexed disodium salt. Company B contended that marketing or use of those products would amount to direct or, in the alternative, indirect infringement in the United Kingdom, France, Italy and Spain.
After a four-day trial the High Court rejected both allegations. The Court of Appeal reversed in part, holding that indirect but not direct infringement would occur. Company B appealed and Company A cross-appealed to the Supreme Court.
Legal Issues Presented
- Whether the use of pemetrexed salts other than pemetrexed disodium (or the free acid) in combination with vitamin B12 constitutes direct infringement of the patent claims when interpreted in accordance with Article 69 EPC 2000 and its Protocol on Interpretation, including the requirement to take account of “equivalents”.
- Whether, if direct infringement is denied, supply of Company A’s products would amount to indirect infringement under section 60(2) of the Patents Act 1977 (and corresponding foreign provisions) when the products are dissolved in saline before administration.
- The extent, if any, to which a court may rely on statements made during prosecution of the patent (the “prosecution history”) when determining claim scope or the reach of the doctrine of equivalents.
Arguments of the Parties
Company B’s Arguments
- The inventive teaching is the safe administration of pemetrexed with vitamin B12; the sodium cation is immaterial. Therefore products using any pemetrexed salt (or the diacid) fall within the claim by equivalence.
- Even if not literally infringing, Company A’s products will be dissolved in saline before use, generating pemetrexed disodium in solution and thus indirectly infringing.
- The prosecution history does not bar reliance on the doctrine of equivalents; amendments were driven by EPO disclosure objections, not an intention to exclude other salts.
Company A’s Arguments
- The claims are expressly limited to “pemetrexed disodium”; other salts or the free acid lie outside the patent by their ordinary meaning.
- The “Improver questions” (as previously applied by English courts) require that it be obvious at the priority date that the variant works; that is not satisfied here because a chemist would need experimental salt-screening.
- Prosecution amendments show a deliberate decision to confine the monopoly to the disodium salt.
- No indirect infringement arises: a saline solution containing multiple ions is not “pemetrexed disodium” within the claim.
Table of Precedents Cited
| Precedent |
Rule or Principle Cited For |
Application by the Court |
| Case 1 – House of Lords, [1982] RPC 183 |
Introduced purposive construction; rejection of strict literalism when minor variants make no material difference. |
Used to show that claim scope may extend beyond literal wording where strict compliance was not intended. |
| Case 2 – High Court, [1990] FSR 181 |
Formulated three “Improver” questions for assessing equivalents. |
The Court reformulated those questions to lower the threshold for equivalence and adopted them as guidance. |
| Case 3 – House of Lords, [2005] RPC 9 |
Endorsed purposive construction; sceptical of a U.S-style doctrine of equivalents and discouraged file-wrapper reliance. |
Supreme Court recognised need to revisit that approach in light of EPC 2000 Article 2 and evolved foreign jurisprudence. |
| Case 4 – Supreme Court (UK), [2013] Bus LR 565 |
Encouraged harmonisation with approaches of other EPC states. |
Cited to justify considering German, French, Dutch, Italian and Spanish practice on equivalents. |
| Case 5 – 19th-century authorities (e.g., (1843) 1 WPC 585) |
Historical recognition that “pith and marrow” of an invention may be infringed despite immaterial variations. |
Demonstrated that UK law has long accepted infringement by immaterial variants. |
Court's Reasoning and Analysis
1. Two-step framework. The Court separated (i) literal infringement by normal interpretation and (ii) infringement by immaterial variation (“equivalents”). If either is satisfied, infringement is found.
2. Literal meaning. On ordinary construction the claims cover only pemetrexed disodium; therefore Company A’s products do not literally infringe.
3. Reformulated equivalence test. The traditional “Improver” questions were recast:
- Does the variant achieve substantially the same result in substantially the same way?
- Knowing that the variant so functions, would this be obvious to the skilled person at the priority date?
- Would the skilled person nevertheless conclude that strict compliance with the literal wording was intended?
All three products satisfied Questions 1 and 2: they deliver the same pemetrexed anion with vitamin B12 and it would be routine to expect alternative salts or the free acid to work. As to Question 3, a rational patentee would not deliberately confine protection to the sodium salt because the specification emphasised the antifolate class generally and contained no teaching that sodium was critical. Hence strict compliance was not intended.
4. Prosecution history. The Court held that file-wrapper material is normally irrelevant save where (i) the patent is otherwise ambiguous and the file plainly resolves the point, or (ii) the patentee’s unequivocal disclaimer makes it unfair to ignore. Neither situation applied. The amendments were driven by disclosure objections, not by any disclaimer of other salts.
5. Indirect infringement. Even had direct infringement failed, supplying the products would be indirect infringement. When dissolved in saline (a step Company A knows occurs before administration) the solution contains pemetrexed anions with sodium counter-ions in ≥2:1 ratio, forming “pemetrexed disodium” within the meaning of the patent. Section 60(2) therefore applies.
6. Foreign designations. Considering French (moyens généraux doctrine), Italian and Spanish law (which broadly follows the UK’s purposive approach), the Court concluded that direct infringement likewise occurs in those jurisdictions.
Holding and Implications
HOLDING: the appeal is ALLOWED; the cross-appeal is DISMISSED.
Company A’s products directly infringe the patent in the United Kingdom, France, Italy and Spain. If direct infringement were absent, indirect infringement would nonetheless be established. The judgment:
- Re-defines the United Kingdom test for infringement by equivalents, aligning it more closely with continental European approaches.
- Limits, but does not exclude, recourse to prosecution history.
- Confirms that routine post-marketing preparation steps (e.g., dilution in saline) can ground indirect infringement.
The decision strengthens patentees’ protection against immaterial design-around strategies but preserves legal certainty by imposing a structured three-question test. No new statutory rule was created, but judicial clarification of Article 69 EPC and its Protocol will guide future infringement litigation.