Supplementary protection certificates (SPCs) may seem like a niche area of patent law, but they are vital to patent owners to extend the protection afforded to a pharmaceutical product in return for the time it takes to get such products through regulatory procedures and then to market. 

So the approach of the Court of Appeal of England and Wales (CoA) on availability of SPCs for second medical use patents in its late January decision in Merck Serono v Comptroller-General of Patents case [2025] EWCA Civ 45, was keenly anticipated by innovators and generic manufacturers alike. This decision confirmed that the court could not deviate from previous binding (UK) precedent on second medical use SPCs, even where these were based on pre-Brexit CJEU (Court of Justice of the European Union) law. In doing so, the court noted that even if it could deviate from its own previous case law, it would not choose to do so in this case.

An SPC is a sui generis intellectual property right that serves as an extension to a patent right in the European Economic Area (EEA). It enters into force after expiry of the patent upon which it is based. It serves to protect medicinal products in particular, and was introduced to encourage research and innovation by compensating for the long time needed to obtain regulatory approval for medicinal products in most EEA jurisdictions.

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. At the patent office, 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. 

The SPC was therefore denied by the UK Intellectual Property Office, and the hearing officer’s 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.

Santen concerned a similar fact scenario. In deciding the case, the CJEU held that Article 3(d) of the SPC regulation “must be interpreted as meaning that a marketing authorisation cannot be considered to be the first marketing authorisation, for the purpose of that provision, where it covers a new therapeutic application of an active ingredient, and that active ingredient has already been the subject of a marketing authorisation for a different therapeutic application”. 

Santen was also referred to and accepted as precedent subsequently in Newron Pharmaceuticals v The Comptroller in 2024. Nonetheless, there was some expectation the UK CoA might adopt a fresh, innovator-friendly approach if presented with the same issue again, especially in light of LJ Arnold’s own comments in Abraxis Sciences v Comptroller General of Patents (2017), where he noted that he considers that SPCs should be available for new applications (i.e. new therapeutic uses) of old active ingredients.

Merck’s appeal to the CoA was based on a single ground – that Santen is wrongly decided and that the CoA should depart from it. There was also 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 therefore not open to the court to diverge from this precedent. Indeed, divergence is an exercise that involves satisfying a number of factors 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’ the SPC regime attempts to perform. 

In particular, 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”.

The decision confirms alignment with the EU’s position on SPCs for second medicinal use products, and seems to have put the issue of second medical use SPCs to rest in the UK, at least for now. Even if not the change in approach hoped for by some, it provides some much-needed certainty for players in the market, the value of which cannot be underestimated in the world of SPCs. 

Priyanka Madan is a senior associate at Herbert Smith Freehills in London and Milan.