Merck Serono v Comptroller-General of Patents (EWCA, [2025] EWCA Civ 45, 2025)

Dhenne Avocats · 11 October 2026

Our analysis

Summary

The Court of Appeal upheld the refusal of a supplementary protection certificate (SPC) sought by Merck Serono for cladribine in the treatment of multiple sclerosis, because earlier marketing authorisations (MAs) existed for the same active ingredient in another indication (para 1). It held that it could not depart from Santen (C-673/18), since its own decision in Newron had applied that judgment as part of its ratio decidendi (paras 14 and 15), and added that it would not have departed from Santen even had it been free to do so (paras 16, 57 and 98). For holders of second medical use patents, the judgment confirms that in the United Kingdom after Brexit a new indication for an already authorised active ingredient does not open the way to an SPC.

Facts and procedure

The application relied on European patent EP 1 827 461, relating to the use of cladribine for treating multiple sclerosis, and on a 2017 MA for MAVENCLAD, indicated for highly active relapsing remitting multiple sclerosis (para 1). Two earlier MAs had been granted for medicinal products containing cladribine, LEUSTAT in 1995 and LETAK in 2004, for hairy cell leukaemia (para 1). Filed in 2018, before Brexit and before Santen, the application was refused on 26 May 2023 by the Comptroller’s Hearing Officer (BL O/0484/23), who followed Santen (para 4). A distinct argument based on a legitimate expectation under Neurim failed before the Hearing Officer and the Patents Court and was not pursued further (para 4). The appeal rested on a single ground: Santen was wrongly decided and the court should depart from it (para 5).

The applicable law

Article 3(d) of Regulation 469/2009, now assimilated law, requires the MA relied on to be the first authorisation to place the product on the market as a medicinal product, the product being defined in Article 1(b) as the active ingredient or combination of active ingredients (paras 23 and 25). Santen and the earlier CJEU case law are assimilated EU case law under section 6 of the European Union (Withdrawal) Act 2018 (para 8). SI 2020/1525 allows the Court of Appeal to depart from such case law applying the 1966 Practice Statement test used by the Supreme Court, unless it is bound by post-transition case law which applies it (paragraph 4(2)) (paras 10 to 12).

Question

Could, and should, the Court of Appeal depart from Santen and return to the teleological approach of Neurim (C-130/11), so as to allow an SPC based on a new therapeutic application of an already authorised active ingredient?

Decision

The appeal was dismissed unanimously (paras 58, 59 and 99). Birss LJ held that Newron, by choosing to follow Santen rather than Neurim, applied Santen as part of its ratio, even though Article 3(b) rather than Article 3(d) was in issue there; paragraph 4(2) of the 2020 Regulations therefore removed the power to depart (paras 14 and 15). Lewison LJ reached the same conclusion under the ordinary rules of precedent: the court is bound by its own decisions under Young v Bristol Aeroplane, and Newron was not decided per incuriam (paras 79 to 88). On the merits, Birss LJ considered that the lack of consistency complained of was caused by Neurim (para 52), that Merck’s approach ignored public health and the interests of third parties (para 53) and that the result sought could only be achieved by legislation (para 54). Santen restored a measure of coherence to the scheme and reduced the legal uncertainty caused by Neurim (para 57). Arnold LJ added that the assimilated Regulation has not been relevantly amended, that there is no realistic prospect of the CJEU reversing Santen, and that Merck cited neither academic criticism nor supportive national decisions (para 59).

Key points for practice

• In the United Kingdom, an MA covering a new therapeutic application of an active ingredient already authorised for another indication is not the first MA for the purposes of Article 3(d) (paras 51 and 57).
• Where a post-transition Court of Appeal decision has applied assimilated EU case law, the Court of Appeal can no longer depart from it; that power remains with the Supreme Court (paras 12 and 15).
• The power to depart from assimilated case law is exercised with great caution: disagreement with the outcome is not enough (para 17).
• Practical point: protection for a new indication of an already authorised molecule cannot rely on a UK SPC, the court regarding any change on this point as a matter for the legislature (para 54).

Provisions applied

Regulation (EC) No 469/2009

Arts 1, 3 and 4

National law

European Union (Withdrawal) Act 2018, section 6; European Union (Withdrawal) Act 2018 (Relevant Court) (Retained EU Case Law) Regulations 2020 (SI 2020/1525); Practice Statement (Judicial Precedent) [1966] 1 WLR 1234

Case law cited

CJEU, Santen (C-673/18); CJEU, Neurim (C-130/11); CJEU, Pharmacia Italia (C-31/03); CJEU, Yissum (C-202/05); CJEU, MIT (C-431/04); CJEU, Abraxis (C-443/17); CJEU, Medeva (C-322/10); Newron Pharmaceuticals v Comptroller [2024] EWCA Civ 128; Young v Bristol Aeroplane [1944] KB 718; Morelle v Wakeling [1955] 2 QB 379

Related decisions

• Santen, 9 July 2020, the CJEU judgment from which the Court of Appeal declined to depart.
• Neurim, 19 July 2012, overruled by Santen and relied on by Merck.
• Abraxis, 21 March 2019, an attempt to confine Neurim, analysed by the court.
• Medeva, 24 November 2011, cited as an example of the teleological approach.

Prepared by Dhenne Avocats from the text of the decision (National Archives, Find Case Law), consulted on 11 October 2026. Only the official text is authoritative.