Merck v Merck: the saga continues as UK Court of Appeal confirms breach of coexistence order

The Court of Appeal has handed down its latest decision in the long-running dispute between the two Merck pharmaceutical businesses – Merck KGaA v Merck Sharp & Dohme LLC and Merck & Co Inc [2025] EWCA Civ 343. The appeal concerned the use of the trade mark "Merck" in the UK and whether certain online activities breached a 2020 order implementing an earlier High Court ruling. Lord Justice Arnold, with whom Lord Justice Phillips and Lady Justice Andrews agreed, dismissed all four grounds of appeal.

This judgment provides important guidance on the role of declaratory relief in trade mark enforcement, the meaning of "targeting" in an online context, and the interpretation of exemptions in coexistence agreements. It also re-emphasises the challenges of maintaining long-term coexistence arrangements in a digital world.

A tale of two Mercks

As discussed in my previous blogs on the Merck saga (see here and here), this case stems from the unusual historical background of two major pharmaceutical businesses operating under the same name in different parts of the world.

Merck Global, the German-based business, traces its origins back to 1668. Merck US began as an offshoot of Merck Global in 1889 and later became fully independent, now operating under the names Merck Sharp & Dohme (MSD) and Merck & Co, Inc. The businesses reached a coexistence agreement in 1970 (with a protocol in 1975) which remains binding and governs use of the "Merck" name worldwide. In short, Merck Global holds rights outside the USA, Canada, Cuba and the Philippines, while Merck US may use "Merck" only within those territories.

The digital age has challenged the clarity of that division. Since 2013, Merck Global has brought proceedings in the UK for breach of contract and trade mark infringement, leading to a series of important judgments from both the High Court and the Court of Appeal. The most recent round focused on whether online and email use by Merck US breached a 2020 court order (the “Final Order”) which enforced the terms of the 1970 Agreement.

A low-key route to coexistence enforcement?

Merck Global applied to the High Court for declaratory relief to determine whether 55 alleged instances of "Merck" branding, identified in an annexed schedule, breached paragraphs 2 and/or 3 of the Final Order. These related mainly to online content, including websites, job advertisements, safety data sheets and news releases, some of which were available to UK users.

At first instance, the judge (Edwin Johnson J) upheld 17 of the 33 alleged rows of breach. He granted a declaration that those acts did amount to breaches but declined to make declarations in respect of the remaining acts, which were not proved to be in breach.

Merck US appealed, arguing, among other things, that the proper route to resolve alleged breaches of a court order was via contempt proceedings under CPR Part 81. The Court of Appeal disagreed. It found that declaratory relief was a valid and proportionate means of clarifying whether past acts were in breach, particularly where no sanctions were sought. As Lord Justice Arnold noted, requiring parties to resort to contempt proceedings in every instance would unnecessarily escalate disputes. The Court also accepted an undertaking from Merck Global not to pursue contempt for the historic breaches found.

Targeting and trade mark use in the UK

Merck US also argued that even if UK users could access the impugned materials, they were not specifically targeted at the UK and thus fell outside the scope of the Final Order. The Court of Appeal rejected this and upheld the High Court’s detailed fact-based analysis. For instance, UK-specific job adverts and safety data sheets hosted on merck.com were clearly targeted at UK users, even if accompanied by disclaimers or pop-ups stating otherwise.

This approach aligns with the Supreme Court’s decision in Lifestyle Equities v Amazon [2024] UKSC 8, which confirmed that targeting is a fact-sensitive exercise. Here, it was not enough to include disclaimers or pop-ups, the overall context, user journey and the nature of the content were all relevant. The Court held that some uses of “Merck” on non-UK-specific sites could still constitute use in the UK, thus breaching the coexistence terms.

On the issue of trade mark use, the Court upheld the finding that where "Merck" was used in promotional materials relating to the pharmaceutical business, even in the absence of direct sales, it still constituted use in the course of trade in the UK.

Interpreting the carve-outs

The judgment also clarifies the scope of various exemptions in the Final Order. For example:

• Paragraph 4(b), allowing links from "UK-specific" MSD-branded websites to merck.com, was found not to apply where the website in question (e.g. msd.com) was global in nature and not UK-specific.

• Paragraph 4(d), permitting use of @merck.com emails by staff outside the UK, did not extend to generic email addresses.

• Paragraph 4(h), permitting inadvertent breaches to be remedied within 7 days, did not apply where breaches arose from deliberate policy choices, even if those choices were made in the mistaken belief that they were compliant.

These distinctions highlight the importance of precision and evidence when relying on carve-outs in coexistence or court orders.

What does this mean?

This case is yet another reminder of how complex it is to maintain coexistence arrangements across digital platforms. Technologies evolve, boundaries blur, and content becomes increasingly global in its reach. Even with detailed agreements and court orders in place, enforcement remains a moving target.

For trade mark owners operating under historic coexistence arrangements, there are several key takeaways:

• Online use must be regularly reviewed to ensure compliance with jurisdiction-specific restrictions.

• Targeting is about substance, not form—disclaimers or pop-ups may help but are not determinative.

• Declaratory relief is a useful tool for clarifying disputes where contempt proceedings would be disproportionate.

• Evidence matters—defending against breach allegations requires clear evidence of site design, user journey and internal compliance policies.

As this case illustrates, coexistence strategies must adapt alongside technology and user expectations. What worked in the 1970s—or even in the early 2000s—may not be enough in an era of AI search, dynamic websites, and cross-border accessibility. Businesses should revisit their digital branding strategies to ensure they remain both effective and compliant.

To find out more about the issues raised in this blog contact Rosie Burbidge.