A Swiss biotech company plans a Phase III oncology trial. Germany. France. The Netherlands. And the UK, where three specialized cancer centers offer access to patient populations essential for enrollment targets. Before 2021, the UK sites would have fallen within the same regulatory architecture as the continental European sites. As of Q1 2026, they do not. The clinical trial agreement signed two years ago contemplated coordination between Switzerland and "the EU." That formulation no longer describes reality.
1. How Do Three Regulatory Submissions Interact?
The EU Clinical Trials Regulation establishes a unified authorization procedure through the Clinical Trial Information System.1Regulation (EU) No 536/2014 of the European Parliament and of the Council of 16 April 2014 on clinical trials on medicinal products for human use [2014] OJ L158/1 (EU CTR). Switzerland, outside the EU, requires separate authorization under the Humanforschungsgesetz.2Bundesgesetz über die Forschung am Menschen (Humanforschungsgesetz, HFG) vom 30. September 2011 (SR 810.30). The UK, post-Brexit, operates under its own framework; as of January 2026 the Medicines for Human Use (Clinical Trials) Regulations 2004 (SI 2004/1031) as amended, with substantially revised regulations expected to come into force in spring 2026.3Medicines for Human Use (Clinical Trials) (Amendment) Regulations 2025 (SI 2025/538), in force 28 April 2026.
Three jurisdictions. Three regulatory submissions. Three timelines. The EU CTR establishes coordinated assessment among Member States; neither Switzerland nor the UK participates in that coordination. If German and French regulatory authorities request protocol modifications through the CTIS, those modifications must be separately submitted to Swissmedic and the MHRA. Whether Swiss and UK authorities will accept the EU-mandated changes, or impose their own, depends on the nature of the modification and the regulatory posture of each authority.
Trilateral coordination requires parallel submissions to authorities that do not share authorization decisions
The UK's anticipated clinical trials framework introduces concepts that diverge from both EU and Swiss approaches. The "notifiable trial" pathway would permit MHRA authorization without detailed assessment for certain lower-risk trials. The EU CTR establishes a differentiated regime for low-intervention clinical trials, defined in Art. 2(2)(3) EU CTR, with reduced documentation and reporting requirements dispersed across multiple provisions,4Art. 2(2)(3) EU CTR (low-intervention clinical trial definition); Recital 11 (reduced requirements). but the UK approach differs in scope and procedural streamlining. Swiss law contains no equivalent simplified pathway. If a trial qualifies for expedited authorization in one jurisdiction but requires full assessment elsewhere, the clinical trial agreement must address these fundamentally different authorization processes. The regulatory divergence extends, inter alia, to GCP compliance standards themselves; the UK will implement ICH E6(R3) on its own timeline, while EU and Swiss implementation timelines differ.
Regulatory divergence extends beyond authorization procedures to the parallel structures governing ethical review. Under the EU CTR, Art. 4 establishes the principle that ethics review is integrated into the Member State's authorization decision; Art. 5–14 set out the coordinated assessment procedure.5Art. 4 EU CTR (n 1) (integration principle); Art. 5–14 EU CTR (coordinated assessment procedure); HFG (n 2), Art. 51–55 (cantonal ethics committees). Swiss law assigns review to the competent cantonal ethics committee (Kantonale Ethikkommission) under Art. 51–55 HFG, operating independently of Swissmedic's regulatory assessment. The UK's HRA provides a single UK-wide ethics opinion through Research Ethics Committees. These structural differences (EU coordinated, Swiss cantonal, UK centralized) create the possibility that ethics committees reach different conclusions on informed consent form language, data retention periods, or participant compensation. The clinical trial agreement must address which ethics committee decisions take precedence when they conflict.
Informed consent requirements compound the divergence. The EU CTR establishes detailed consent provisions under Art. 28–35, including specific requirements for incapacitated subjects, minors, and emergency situations.6Art. 28–35 EU CTR (n 1) (informed consent, including Art. 31 incapacitated subjects, Art. 32 minors, Art. 35 emergency situations); cf Art. 16–18 HFG (Swiss consent framework); see also Art. 32–35 HFG (further use of already-collected biological material and health-related personal data). Swiss law under Art. 16–18 HFG contains its own consent framework with distinctive features, including provisions governing the further use of already-collected biological material and health-related personal data under Art. 32–35. UK requirements are evolving under the forthcoming framework. A trilateral trial needs informed consent forms that simultaneously satisfy all three regimes, or distinct forms for each jurisdiction, with the consequent risk of inconsistency in what participants across sites are told about the same trial.
The fragmentation is not, however, complete. All three jurisdictions participate in ICH harmonization, and substantial practical cooperation continues. The MHRA has publicly indicated willingness to consider EU assessments. Swissmedic routinely accepts foreign GMP inspection reports. The EU-UK Trade and Cooperation Agreement includes medicinal products cooperation provisions under Annex TBT-2, establishing a working group and information exchange mechanisms.7TCA [2021] OJ L149/10, Annex TBT-2 (Medicinal Products), Art. 12 (Working Group). These mechanisms do not restore mutual recognition of clinical trial authorizations, but they provide informal pathways that may reduce practical divergence even where formal recognition is absent.
2. Which Data Protection Regime Governs?
Clinical trial data flows continuously: from investigator sites to sponsors, from sponsors to contract research organizations, from CROs to regulatory authorities. When trial sites span three jurisdictions with three data protection regimes, each flow requires separate analysis (see also Insight 03; and Insight 09 on Art. 271 StGB implications when foreign authorities request access to Swiss-held trial data).
The EU operates under the GDPR. The UK operates under UK GDPR, substantially similar but not identical, and subject to ongoing adequacy assessment by the European Commission.8Commission Implementing Decision (EU) 2021/1772 (UK adequacy), renewed 19 December 2025 until 27 December 2031. Switzerland's adequacy status under EU law dates to Decision 2000/518/EC; the DSG entered into force on 1 September 2023, and the Commission has confirmed continued adequacy recognition.9Commission Decision 2000/518/EC (Swiss adequacy); DSG (SR 235.1) in force 1 September 2023. As of early 2026, data can flow relatively freely among all three jurisdictions, but adequacy decisions are not permanent. The UK adequacy framework remains subject to ongoing European Data Protection Board scrutiny, particularly regarding UK surveillance laws and potential divergence from GDPR standards. Future adequacy assessments may reach different conclusions.
If UK adequacy were revoked in a future assessment, data transfers from EU sites to a UK-based CRO would require Standard Contractual Clauses or other transfer mechanisms, adding contractual complexity and potentially delaying data flows critical for safety monitoring. Even if adequacy is maintained, future renewals could impose enhanced monitoring conditions or additional compliance requirements that pre-2026 trial agreements may not contemplate. The clinical trial agreement must address not only existing transfer mechanisms (adequacy decisions, Standard Contractual Clauses, and binding corporate rules) but also contingency provisions for adequacy changes, whether revocation, conditional renewal, or new compliance obligations.
Consider a specific data flow: genetic sequencing data from a French site, processed by a Swiss sponsor, shared with a UK laboratory for biomarker analysis, then transmitted to the MHRA as part of a safety report. Four jurisdictions touch that data. If the sponsor's agreement with the UK laboratory was drafted before Brexit, it likely references GDPR compliance without addressing the UK's separate data protection regime. If the site agreement with the French investigator assumes data remains within the EU, it may not contemplate transfers to a UK processor classified as a third country recipient.
Transparency obligations introduce a further asymmetry. The EU CTR requires public disclosure of trial results, protocol summaries, and certain clinical study reports through the CTIS public portal under Art. 37 and Art. 80–82.10Art. 37(4) EU CTR (n 1) (results submission within one year); Art. 80–82 (EU portal and database infrastructure). Neither Swiss law nor UK law imposes equivalent mandatory public disclosure through a centralized system. For a trilateral trial, information publicly available through CTIS about EU sites may need to be reconciled with confidentiality provisions in UK and Swiss site agreements; sponsors face the risk that commercially sensitive trial information disclosed under EU transparency obligations becomes available to competitors, while equivalent information from UK and Swiss sites remains protected.
The European Health Data Space (EHDS), adopted as Regulation (EU) 2025/327, may create additional obligations regarding secondary use of clinical trial data generated at EU sites, obligations that have no parallel for UK or Swiss site data.11Regulation (EU) 2025/327 of the European Parliament and of the Council establishing the European Health Data Space [2025] OJ L 2025/327, ch IV (secondary use of electronic health data). And as clinical trial data management increasingly relies on cloud-based EDC systems and CTMS platforms, data localization requirements and the US CLOUD Act introduce additional jurisdictional complexity to the data flow analysis.
Data transfer mechanisms address one dimension of trilateral complexity. The underlying sponsor structure, and its liability implications, presents distinct challenges.
3. Where Does Sponsor Liability Fall?
The EU CTR requires sponsors not established in the Union to designate a legal representative within an EU Member State, subject to Member States' option under Art. 74(2) to accept a contact person instead for trials conducted solely on their territory.12Art. 74(1) EU CTR; cf Art. 74(2) (Member State opt-out). UK law requires sponsors not established in the UK or an approved country to appoint a legal representative, but this role operates differently from the EU CTR's Art. 74(1); the UK representative serves primarily as a communications addressee and agent for service rather than assuming the sponsor's regulatory liabilities. Swiss law permits foreign sponsors with designated Swiss contact persons.
A Swiss sponsor conducting a trilateral trial might designate its German subsidiary as EU legal representative while maintaining direct sponsor status in the UK and Switzerland. This structure creates asymmetric liability exposure. If a serious adverse event occurs at a UK site, the sponsor faces direct liability under UK law, with no intermediary and no buffer. If a similar event occurs at a German site, Art. 74(1) EU CTR makes the legal representative responsible for ensuring that the sponsor's obligations under the CTR are complied with, language that some interpret as imposing joint and several liability (Gesamtschuld) for regulatory breaches, though the precise scope of this responsibility remains contested in the literature. Whether this extends to civil liability for patient harm (as distinct from regulatory compliance failures) remains a question the regulation does not clearly resolve.
Civil liability for harm arising from clinical trials engages national tort law, with applicable law in cross-border cases determined under the Rome II Regulation.13Regulation (EC) No 864/2007 (Rome II), Art. 4 (general rule), 5 (product liability). The general rule under Art. 4 Rome II points to the law of the country where the damage occurs; the product liability rule under Art. 5 Rome II may apply where the claim relates to the investigational medicinal product itself. The complexity lies not only in what the CTR fails to resolve but in the interaction between regulatory liability frameworks and private international law rules that may point to different national laws for different claims arising from the same adverse event. The German subsidiary's balance sheet may become relevant in ways the Swiss parent did not anticipate when designating it as legal representative. The contractual allocation between parent and subsidiary must account for this asymmetry, and the indemnification provisions must survive scrutiny under both German and Swiss law.
If the sponsor's EU legal representative is also conducting monitoring activities at UK sites, the representative's role shifts between jurisdictions. Acting as a data controller's representative in the EU under Art. 27 GDPR, potentially as a processor when handling UK site data, and as something else entirely under Swiss law, the same entity wears different hats depending on which border the data crosses. Employment contracts, professional liability insurance, and internal compliance procedures drafted for a single regulatory regime may not accommodate this jurisdictional fragmentation.
The sponsor-level contractual structure, moreover, does not exist in isolation. Investigator and site agreements in each jurisdiction must reflect local requirements that differ in substance and form. French site agreements must comply with the Loi Jardé and CNIL data processing requirements. German site agreements must address Arzneimittelgesetz provisions on investigator obligations and institutional liability. UK site agreements must reflect NHS cost attribution requirements and the HRA's model agreements. The clinical trial agreement at the sponsor level must ensure that site-level agreements are locally compliant while maintaining overall trial coherence, a coordination challenge that multiplies with each jurisdiction added to the trial's footprint.
4. What Happens When Amendments Desynchronize?
A trial progresses. Interim analysis suggests a dose modification. The sponsor prepares a substantial amendment. Under the EU CTR, the amendment enters the CTIS and follows coordinated assessment timelines. Under UK law, the amendment requires separate MHRA submission, potentially with different supporting documentation requirements once the 2025 amendments take effect. Under Swiss law, Swissmedic assessment follows its own timeline.
If the EU assessment results in a request for further modification, and the sponsor implements that modification to maintain EU site enrollment, must the UK and Swiss submissions incorporate the EU-mandated changes? If the MHRA accepts the original amendment while Swiss authorities are still reviewing, may UK sites implement the dose change before Swiss sites? The protocol itself may require synchronized implementation across all sites for scientific validity. The regulatory frameworks permit, and may require, asynchronous authorization.
Regulatory timelines no longer synchronize. Contractual provisions must address the consequences
Safety reporting presents similar challenges. The EU CTR establishes specific timelines for Suspected Unexpected Serious Adverse Reaction reporting through the EudraVigilance system. UK law requires MHRA notification through a separate pathway. Swiss law imposes its own pharmacovigilance obligations. A SUSAR occurring at a UK site must be reported to the MHRA within UK timelines, to EU authorities through EudraVigilance for EU sites, and to Swissmedic for Swiss sites. If the clinical trial agreement assigns pharmacovigilance responsibility to a single entity, that entity must maintain parallel reporting capabilities across all three systems.
The coordination questions multiply across several dimensions. If EU regulatory authorities require protocol modifications that UK or Swiss authorities have not requested, the trial agreement must specify whether implementation is required across all jurisdictions or whether jurisdictional divergence is permitted. When authorization timelines differ significantly, contractual mechanisms must address whether sites in faster-approving jurisdictions may begin enrollment before slower jurisdictions authorize.
If one jurisdiction suspends the trial for safety concerns, the agreement must specify whether automatic suspension at sites in other jurisdictions is required. And the contractual allocation of pharmacovigilance responsibility must translate into operational reality, confirming that the sponsor's pharmacovigilance provider can report simultaneously across EU, UK, and Swiss systems with each system's specific requirements.
A further dimension of divergence concerns the investigational medicinal product (IMP) supply chain. Post-Brexit, IMP manufactured in the UK for EU trial sites requires EU-compliant Qualified Person (QP) release; a UK QP release certificate no longer suffices. Conversely, IMP manufactured in the EU for UK sites requires UK-compliant QP release. The TCA's Annex TBT-2 provides for GMP cooperation and information exchange but does not restore mutual recognition of batch release. A Swiss sponsor manufacturing IMP in Basel for all three jurisdictions must comply with three distinct GMP release frameworks (Swissmedic requirements, EU GMP Directive compliance with EU QP release, and UK requirements with UK QP release), and the clinical trial agreement's IMP supply provisions must specify responsibility for ensuring compliant release in each jurisdiction.
The preceding analysis identifies where legal complexity arises. The question for sponsors is whether this complexity is justified by the scientific or commercial value of trilateral arrangements.
5. Whether Trilateral Complexity Justifies the Benefit
Swiss sponsors entering trilateral arrangements face a threshold question that regulatory frameworks do not answer: whether the operational burden of three-jurisdiction coordination justifies the scientific or commercial benefit of including UK sites. The UK offers access to the NHS patient population, specialized research centers, and, under the new framework, potentially faster authorization for certain trial types. These advantages must be weighed against the contractual complexity, data transfer risk, and coordination costs that trilateral trials impose.
The calculation differs for different trial types. A trial requiring rare disease patient populations available primarily in specialized UK centers may justify trilateral complexity. A Phase IV study that could enroll equivalent populations from EU sites alone may not. The clinical trial agreement cannot make this strategic decision, but it must implement whatever decision the sponsor makes, and implementation requires provisions that standard bilateral templates do not contain.
Many existing clinical trial agreements were drafted when the UK remained within the EU's regulatory architecture. Those agreements may assume a bilateral coordination model that no longer reflects the trilateral reality, and the gap between contractual assumptions and regulatory fact tends to surface when something goes wrong. Data transfer provisions present a related exposure: agreements that reference GDPR compliance without addressing UK adequacy status or contingency mechanisms for future assessments may leave sponsors with invisible risk until a transfer is actually challenged.
The interaction between sponsor structure and insurance coverage compounds this exposure. Each jurisdiction imposes distinct insurance or financial security requirements: Swiss law under Art. 13 KlinV (SR 810.305) mandates adequate insurance or equivalent financial security,14Art. 13 Verordnung über klinische Versuche mit Ausnahme klinischer Versuche mit Medizinprodukten (KlinV) vom 20. September 2013 (SR 810.305) (Versicherung oder anderweitige finanzielle Sicherstellung). while the EU CTR's Art. 76 requires insurance or indemnification, and the UK framework introduces its own coverage obligations. A single global clinical trial insurance policy may not satisfy all three sets of requirements, and the contractual allocation of liability across jurisdictions only functions if actual coverage matches. For ongoing trials whose agreements predate the UK's regulatory divergence, identifying what amendments are required to reflect the post-Brexit legal reality becomes the threshold task before any forward planning can proceed.
These questions resist template solutions. Each trilateral arrangement presents unique combinations of trial design, sponsor structure, site distribution, and data flow that require analysis against evolving regulatory frameworks in all three jurisdictions. The contracts drafted in 2019 were not wrong; they addressed the world as it existed. That regulatory environment has materially changed.