Bolar Exemption UK 2026: Scope, Clinical Trial Activities and Biosimilar Strategy

Bolar exemption UK rules are now a frontline compliance question for any pharmaceutical or biotech team preparing a product for the UK market in 2026, because the rapid expansion of biosimilar and biologics pipelines has sharpened the need to know exactly which pre-approval activities fall safely inside the statutory carve-out and which risk infringing a live patent. The core principle is straightforward, certain acts carried out to generate regulatory data do not infringe, but the practical boundaries are where in-house counsel, R&D leaders and regulatory teams get caught out.

This guide maps specific laboratory and clinical activities to the UK statutory position, explains the special pitfalls that arise in biosimilar programmes, and sets out a step-by-step freedom-to-operate (FTO) checklist you can run against your development milestones. Throughout, we pair each activity with plain-English “Practical risk” and “Mitigation” call-outs so the analysis is usable at the bench as well as in the boardroom.

Executive summary, key takeaways

The bolar exemption UK framework is a statutory defence to patent infringement. It allows a party to carry out acts that would otherwise infringe a patent, provided those acts are done for the purpose of generating the data needed to obtain a marketing authorisation for a medicinal product. In practice this covers a substantial range of pre-approval work, analytical testing, comparability studies, non-clinical investigations and clinical trials, as long as the activity is genuinely tied to the regulatory submission rather than to commercial exploitation. The line between permitted development work and prohibited commercial activity is the single most important concept to internalise.

• Generally safe. Analytical and comparability testing, bridging studies, and clinical trials conducted solely to develop and submit data for a marketing authorisation are, as a rule, protected under the carve-out.
• Risky. Stockpiling commercial-scale product, marketing or pre-sale activity, and any use that goes beyond what the regulatory dossier reasonably requires can fall outside the exemption and expose the company to infringement.
• Immediate steps. Document the regulatory purpose of each activity, keep procurement and protocol records, and run a formal FTO assessment before any activity that touches a third party’s live patent at scale.

Legal basis, the Patents Act and statutory text

The starting point for any bolar exemption UK analysis is the Patents Act 1977, and in particular section 60, which defines both what constitutes infringement and the acts that are excluded from it. The relevant carve-outs sit in section 60(5), and the two most important for life-sciences teams are the experimental use provision in section 60(5)(b) and the regulatory-data provisions in section 60(5)(i) and section 60(6D)–(6G).

Section 60(5)(b) and the experimental use wording

Section 60(5)(b) of the Patents Act 1977 provides that an act which would otherwise infringe a patent is not infringing where “it is done for experimental purposes relating to the subject-matter of the invention.” This is the foundational experimental use defence, and it is deliberately broad in concept but narrow in application: the act must be genuinely experimental, and it must relate to the subject-matter of the invention rather than to purely commercial ends.

Alongside the experimental use provision, section 60 contains a dedicated carve-out for acts done for the purpose of a medicinal product assessment. Section 60(5)(i), read with the definitions inserted into section 60, provides that acts that would otherwise infringe do not infringe where they are done for the purpose of a “medicinal product assessment”, broadly, acts done in connection with obtaining or varying a marketing authorisation or carrying out certain health-technology and regulatory assessments. Following amendments that took effect in 2014, the UK provision was widened beyond the older generics-only wording so that it now covers acts done to support a marketing authorisation application in the UK, the EU/EEA or a third country, as well as associated regulatory assessments.

This is the provision most practitioners have in mind when they refer to the “Bolar” exemption. The practical effect is that studies, trials and associated acts carried out to generate data required by a regulator, and to prepare and submit the authorisation dossier, do not infringe a patent even where they use the patented product or process. The statutory test turns on purpose: the activity must be done for the purpose of the relevant medicinal product assessment.

How the experimental use defence sits alongside section 60

The experimental use defence in section 60(5)(b) and the regulatory-data carve-out are complementary but distinct. Experimental use is a long-established concept applied to any genuinely experimental act relating to the invention; it is not limited to medicines. The regulatory-data carve-out, by contrast, is specific to acts aimed at a medicinal product assessment. Many pre-launch pharmaceutical activities can, in principle, be defended under either limb, but the evidential and conceptual tests differ, a point we return to in the dedicated comparison below. For teams building a defensible position, the safest approach is to identify, for each activity, which limb is being relied on and to document the facts that support it.

What the bolar exemption UK covers in practice, an activity map

The doctrine only becomes useful when it is mapped to real work. Below, each category of activity is set out with typical examples, an assessment of whether it is likely covered, and the caveats that matter. Scale, commercial intent and the nexus to the regulatory submission are the recurring variables that determine the answer.

Pre-clinical analytical and comparability testing

This category includes bench assays, cell-based functional assays, physicochemical characterisation and pharmacokinetic or pharmacodynamic analytics carried out to characterise a product and, for biosimilars, to compare it against a reference product. These activities sit comfortably within the bolar exemption UK carve-out and the experimental use defence where they are performed to generate data that supports an application. The purpose is investigatory and submission-linked, not commercial.

Scenario A, in-lab comparability for batch release. A developer runs a suite of analytical assays on pilot batches to establish comparability with a reference biologic for the regulatory dossier. This is characteristically protected activity.

• Practical risk: If the same batches are diverted into commercial channels or used to build commercial inventory, the protective purpose is undermined.
• Mitigation: Segregate development batches, record their intended regulatory use, and keep traceability from manufacture to assay.

Non-clinical studies and bridging studies

Non-clinical toxicology, immunogenicity screening and bridging studies that connect existing data to a new application are part of the regulatory evidence package. Where these studies are conducted to satisfy the regulator’s requirements, they fall within the scope of the carve-out. The nexus to the dossier is usually clear, because the regulator’s guidance dictates the studies required, which itself provides evidence of regulatory purpose.

Clinical trial activities

Sponsor-led clinical trials, bridging clinical data and comparative clinical programmes are permitted where they are conducted for the purpose of a medicinal product assessment. In the UK, clinical trials of medicines require authorisation, and the Medicines and Healthcare products Regulatory Agency (MHRA) oversees the clinical trials authorisation process under the applicable medicines and clinical trials regulations. The existence of an MHRA-authorised trial protocol, framed around the data the authorisation requires, is powerful evidence that the activity is protected under the bolar exemption UK carve-out.

Scenario B, pilot efficacy trial. A biosimilar developer conducts a comparative clinical efficacy trial against the reference product to support its application. Because the trial generates data required for the authorisation, the clinical use of the patented reference product in that trial is ordinarily protected.

• Practical risk: Trials designed, in substance, to seed the market or to support promotional claims rather than to satisfy regulatory data needs may fall outside the carve-out.
• Mitigation: Ensure the protocol objectives map onto the regulator’s data expectations, and avoid protocol features that are only explicable by commercial motive.

Regulatory filing and dossier preparation

Acts that are inseparable from preparing and submitting the authorisation dossier, assembling data, drafting the common technical document and responding to regulator questions, are the paradigm case for protection. These are the activities the clinical trial exemption UK framework and the regulatory carve-out exist to permit. The further an act moves from the submission and towards manufacturing for sale, the weaker the protection becomes.

Scenario C, pre-submission readiness manufacturing. A developer manufactures limited quantities to validate the process and generate stability data for the dossier. This is generally protected. By contrast, manufacturing commercial-scale stock in anticipation of launch, before patent expiry, is a classic red flag.

Biosimilars and the bolar exemption UK, special considerations

Biosimilar programmes concentrate patent risk because, by their nature, they require extensive use of a patented reference product and generate comparative data against it. The scientific expectations for biosimilars are demanding: the EMA’s biosimilar framework sets out that approval rests on a comprehensive comparability exercise demonstrating no clinically meaningful differences from the reference medicine, and the MHRA applies broadly aligned scientific principles for UK authorisations. That scientific reality drives a large volume of reference-product use, which is precisely where the biosimilar bolar uk analysis becomes acute.

Analytical comparability versus functional assays, scope and risks

Analytical comparability, comparing structural and physicochemical attributes, and functional or cell-based assays are the backbone of a biosimilar dossier. Both are strongly aligned with the regulatory purpose test and are ordinarily protected. The risk is not usually the assay itself but the quantity of reference product consumed and the possibility that characterisation work drifts into product development that outlives the submission need.

• Practical risk: Acquiring more reference product than the comparability programme reasonably requires can look like stockpiling or commercial use.
• Mitigation: Scope reference-product procurement to documented study needs, and record the assay plan that justifies each quantity.

Reference product sourcing and use rules

Reference product testing uk raises distinct questions around import, labelling and supplier risk. Sourcing the reference product, potentially across territories, and importing it for comparability work must itself be defensible. Where the acquisition is for the purpose of generating authorisation data, it ordinarily enjoys protection, but the chain of custody and the stated purpose matter a great deal if the activity is later challenged.

Scenario D, cross-border reference sourcing. A UK developer sources reference product from another market to run comparability studies. The import and use are ordinarily protected where they are for the dossier, but the developer should be able to show the regulatory rationale and that quantities match the study design.

• Practical risk: Opaque sourcing, excess quantities, or re-supply to third parties undermine the defence and create supplier-contract exposure.
• Mitigation: Use procurement contracts that state the regulatory purpose, maintain sample traceability, and restrict onward use. Include justified-use statements in internal records.

Immunogenicity and bridging clinical programmes, when patent risk increases

Immunogenicity assessment and bridging clinical programmes consume reference product in patients and generate the comparative clinical data a biosimilar application needs. These are typically protected where they are driven by the regulator’s requirements. Patent risk rises when the clinical programme is larger or more market-facing than the data need justifies, or when early-access or named-patient supply blurs into commercial distribution.

Scenario E, immunogenicity bridging study. A comparative immunogenicity study against the reference product, designed to satisfy the data package, is generally protected activity. Scenario F, expanded access ahead of approval. Supplying product to patients outside a protected trial, before authorisation and patent expiry, is a high-risk activity that is unlikely to be defensible as development work.

For biosimilar teams, the most effective mitigations are structural. Draft study protocols so that every arm and every quantity maps to a stated regulatory objective. Keep procurement and traceability records that connect each unit of reference product to a study. Engage early with the MHRA so that the regulatory rationale for the programme is documented and contemporaneous. And ensure collaboration and supply agreements restrict any use beyond the development purpose.

Experimental use defence vs the bolar exemption UK, a side-by-side comparison

Because the uk experimental use defence and the regulatory-data carve-out overlap in practice, teams often need to decide which they are relying on and why. The distinction matters for the legal test, the evidence required and the activities each comfortably covers.

Legal test and burden of proof

The experimental use defence under section 60(5)(b) turns on whether the act was done for genuinely experimental purposes relating to the subject-matter of the invention. The regulatory carve-out turns on whether the act was done for the purpose of a medicinal product assessment. In both cases the defendant must be able to evidence purpose, and commercial motive is the factor most likely to defeat reliance. Contemporaneous documentation of objectives is, in practice, the determinative evidence.

Typical examples where each applies

Experimental use is the natural home for early research, investigating how an invention works, testing a hypothesis, or finding something out about the patented subject-matter. The regulatory carve-out is the natural home for the structured data generation that a marketing authorisation requires: comparability studies, non-clinical studies and clinical trials tied to the dossier. Many pre-launch biosimilar activities can be defended under either limb, but framing the activity under the right provision strengthens the position.

Risk matrix and pre-launch IP checklist for R&D and legal teams

Turning the doctrine into operational discipline is what protects a programme. The following framework helps R&D and legal teams decide when to escalate and what to keep on file.

Quick decision tree, when to run a formal FTO

1. Does the activity use or require a patented product, process or reference product? If no, document and proceed. If yes, continue.
2. Is the activity done for the purpose of a medicinal product assessment or for genuine experimentation? If no, run a full FTO and consider licensing. If yes, continue.
3. Does the scale, quantity or distribution go beyond what the assessment purpose reasonably requires? If yes, run a full FTO. If no, document the regulatory purpose and proceed.
4. Does any product leave the development pathway, sale, supply, stockpiling, promotion? If yes, this is outside the carve-out; obtain advice before proceeding.

Minimum documentation to defend reliance on the exemption

• Study protocols that state the regulatory objective and map arms and quantities to the data the authorisation requires.
• Procurement records for any reference product, including purpose statements, quantities and chain of custody.
• Study objectives and design rationale that demonstrate experimental or submission purpose rather than commercial intent.
• Regulatory correspondence, including MHRA engagement, evidencing that the activity is driven by the authorisation requirements.
• Segregation records showing development material was not diverted to commercial use.

Tie these records to development milestones: generate them contemporaneously at protocol approval, at procurement, and at study completion, rather than reconstructing them if a dispute arises.

Practical enforcement risks and mitigation tactics

Even a well-run programme can attract a patentee’s attention, particularly where activities are visible through clinical trial registers or regulatory timelines. The following tactics reduce enforcement exposure and prepare the ground if a dispute emerges.

Negotiation, licences and targeted carve-outs in collaborations

Where an activity sits close to the edge of the carve-out, or where a collaboration involves multiple parties, a targeted licence or a contractual carve-out can remove ambiguity. In collaboration and supply agreements, define the permitted development purpose precisely, restrict onward use of patented materials, and allocate responsibility for any infringement risk. A narrow licence covering a specific borderline activity is often cheaper than litigation and gives the programme certainty.

Skinny labels and indications management, UK considerations

Where a reference product’s patents cover specific indications, careful indications management, sometimes described as skinny labelling, can reduce patent exposure at launch by carving protected indications out of the biosimilar’s authorisation. This is a regulatory and patent strategy that must be coordinated across functions, because the labelling, the authorisation and the patent landscape all interact. UK case law on second-medical-use patents and skinny labels shows that the approach reduces but does not automatically eliminate infringement risk, so the strategy should be assessed on the specific patents in issue.

If a risk is identified, the practical next steps are to brief outside counsel with the full activity record, assess the strength of the relevant patents, and decide between designing around, licensing, or challenging validity.

Conclusion, actionable next steps and template FTO questions

The bolar exemption UK framework gives life-sciences teams substantial room to carry out the testing, comparability work and clinical trials needed to bring a product to market, but the protection depends entirely on purpose and proportionality. The practical discipline is to match every activity to a documented regulatory or experimental purpose, to keep scale and distribution within what the assessment purpose requires, and to escalate borderline activities to a formal FTO before they happen. Early engagement with counsel, contemporaneous documentation and coordinated regulatory and patent strategy are what convert the doctrine into a defensible position. Use the following starter FTO questions with your R&D and regulatory teams:

• Which tasks in this programme require the patented reference product, and in what quantity?
• Is each use of a patented product or process tied directly to data a medicinal product assessment requires?
• Are any activities, in substance, sale-oriented, promotional or market-seeding rather than developmental?
• Does the quantity of reference product procured match the documented study design?
• Can we show a contemporaneous protocol and objective for each study relying on the carve-out?
• Is any development material at risk of entering commercial channels before patent expiry?
• Have we engaged the MHRA so the regulatory rationale is documented?
• Do our collaboration and supply contracts restrict use of patented materials to the development purpose?

Sources

1. Patents Act 1977, Section 60
2. Human Medicines Regulations 2012
3. MHRA, Clinical trials for medicines: apply for authorisation in the UK
4. EMA, Biosimilar medicines overview
5. Chartered Institute of Patent Attorneys (CIPA)