Could we…and would we..? UK CoA confirms that it is bound by previous precedent on second medical use SPCs

The UK Court of Appeal handed down its decision in the much awaited Merck Serono v Comptroller-General of Patents case  [2025] EWCA Civ 45 on 28 January. Not only did the three-judge bench of LJs Lewison, Arnold and Birss confirm that the court could not deviate from previous binding (UK) precedent on second medical use Supplementary Protection Certificates (SPCs), the court also noted that even if it could deviate from its own previous case law, it wouldn’t choose to do so in this case.

The case concerned Merck's application for an SPC covering cladribine for the treatment of multiple sclerosis, based on their 2017 marketing authorisation for the product Mavenclad®. The application was held not to meet the requirements of article 3(d) of the relevant Regulation ((EC) No. 469/2009) because of the existence of an earlier marketing authorisation for a medicinal product containing cladribine as an active ingredient. In fact there were two earlier marketing authorisations, one for a medicinal product called Leustat® issued in 1995 and another for a medicinal product called Letak® issued in 2004. Each of these authorisations were for a medicinal product containing cladribine as an active ingredient for the treatment of hairy cell leukaemia.

Mercks' SPC application was denied by the UKIPO, and the Hearing Officer decision was upheld by the High Court, largely on the basis that the CJEU case law in Santen C-673/18 (which was retained post-Brexit) precludes the grant of SPCs on the basis of second medical use marketing authorisations. Merck's appeal to the CoA was based on a single ground – that Santen is wrongly decided and that the Court of Appeal should depart from it. As well as the question of departure itself, there was a prior question whether it is open to this court to depart from Santen at all, given the CoA's own previous decision in Newron Pharmaceuticals v The Comptroller in 2024, in which the court had already applied the Santen reasoning to dismiss an SPC application.

The CoA held that first, it could not diverge from Santen in the present circumstances – even though it is within the power of the CoA to deviate from retained EU law in certain circumstances, this was not the case when the EU law in question (i.e. Santen) had already been adopted by a previous (binding) decision of the court – here, the CoA had already adopted Santen when deciding the Newron case, and as the CoA is generally bound by its own previous decisions, it was not open to the court to diverge from this precedent. Indeed, diverging from previous precedent is an exercise that involves satisfying number of factors (such as considering if the previous case was decided per incuriam), which are not satisfied in the present case.

Further, the CoA held that even if it could diverge from Santen, it would not in the present circumstances. Considering the scheme of the SPC regulation and previous case law in its entirety, the court held that Santen was correctly decided, and the (un)availability of SPCs for second medical uses was a feature of the 'balancing act' that the SPC regime attempts to perform. The court noted that "Santen is a decision which brought the scheme of the Regulation back into a measure of coherence, and substantially reduced the legal uncertainty caused by [the CJEU's previous case law in] Neurim." Arnold LJ further noted that "…it remains the will of Parliament that the legislation should continue to be harmonised with that of the EU. In those circumstances, the UK courts should continue to interpret the legislation in harmony with the Court of Justice unless convinced that the Court of Justice’s interpretation is wrong."

Priyanka Madan, Senior Associate and specialist in SPC and pharmaceutical regulatory issues, commented:  

"There was some speculation that the UK court might choose to diverge from the CJEU on this crucial point of second medical use SPCs, setting the UK apart as a more innovation and research-friendly jurisdiction when it comes to the grant of SPCs. This has not been the case. However, the decision confirms alignment with the EU, which provides some much-needed certainty for players in the market. The value of certainty cannot be underestimated in the world of SPCs. "