The Lock Review and Clinical Negligence: Collaborating on Causation with Scientific and Medico-Legal Experts

In clinical negligence litigation, causation disputes often hinge on the interplay between scientific principles and clinical practice. The Lock Review, commissioned by the UK government to examine scientific evidence in the justice system, has highlighted the need for rigorous, multidisciplinary collaboration where causation is contested. For instructing solicitors, integrating scientific experts—such as pathologists, radiologists, or toxicologists—with clinical subspecialists—including oncologists, neurologists, or cardiologists—can strengthen evidential frameworks in complex claims, personal injury matters, and inquests.

Clinical Context: Scientific Evidence in Causation

Causation in clinical negligence requires establishing a link between alleged breach of duty and harm suffered, often amid pre-existing conditions or delayed presentation. Scientific evidence addresses critical questions such as:

• Whether delayed cancer diagnosis materially affected prognosis (e.g., tumour staging, metastatic spread).
• Whether missed aortic dissection on imaging altered clinical outcome (e.g., survival rates, surgical complications).
• Whether toxic exposure (e.g., occupational or environmental) contributed to neurological or psychiatric conditions.
• Whether traumatic brain injury (TBI) caused long-term cognitive impairment, distinct from pre-existing neurodegenerative disease.

These questions demand input from both scientific experts—interpreting laboratory findings, imaging, or pathology—and clinical subspecialists—contextualising findings within the patient’s treatment trajectory.

Frameworks for Scientific-Clinical Integration

Key clinical frameworks guide evidence integration in causation disputes:

• Oncology: NICE’s 2-week-wait referral guidelines benchmark timely diagnosis. Scientific evidence—histopathological grading, molecular markers, or imaging-based tumour volumetrics—quantifies prognosis impact. For example, delayed breast cancer diagnosis may be assessed using Nottingham Prognostic Index (NPI) scores, incorporating tumour size, grade, and lymph node status.
• Cardiology: In missed myocardial infarction (MI) or aortic dissection cases, troponin pathways, ECG interpretation, and imaging (e.g., CT angiography) are critical. The CHA₂DS₂-VASc score informs stroke risk in atrial fibrillation (AF) disputes, while aortic dissection red flags (e.g., widened mediastinum on chest X-ray) underpin breach arguments.
• Neurology: In stroke litigation, thrombolysis windows (e.g., 4.5 hours for intravenous alteplase) and imaging (e.g., ASPECTS scoring on CT perfusion) are pivotal. For TBI, the Glasgow Outcome Scale (GOS) and advanced imaging (e.g., diffusion tensor imaging) differentiate acute trauma from pre-existing pathology.
• Toxicology and Environmental Medicine: In alleged harmful substance exposure (e.g., asbestos, lead), scientific experts analyse biological monitoring data, histopathological findings (e.g., mesothelioma), or epidemiological studies. Clinical subspecialists, such as neurologists or respiratory physicians, contextualise findings within symptoms and functional impairment.

Legal Relevance: Causation Tests and Expert Evidence

Under English law, causation is assessed using the but-for test (Barnett v Chelsea and Kensington HMC [1969]) or the material contribution test (Bailey v Ministry of Defence [2008]; Williams v Bermuda Hospitals Board [2016]). In loss of chance cases, Gregg v Scott [2005] principles apply, requiring experts to quantify reduced survival or recovery prospects. Montgomery v Lanarkshire [2015] further emphasises the need for experts to address material risks in consent disputes.

The Lock Review stressed the importance of robust, accessible scientific evidence. Expert witnesses must:

• Explain complex concepts in clear language.
• Integrate scientific findings with clinical guidelines (e.g., NICE, Royal College standards).
• Address legal causation tests (e.g., material contribution, loss of chance) with reference to evidence.
• Engage in CPR Part 35.14 joint discussions to narrow issues and identify agreement areas.

Instructing solicitors should select experts experienced in medico-legal methodology. For example, a radiologist opining on a missed fracture must articulate how imaging findings relate to symptoms, functional impairment, and prognosis—not merely describe radiological appearance.

Common Pitfalls in Expert Instruction

Avoiding these pitfalls strengthens causation arguments:

• Over-reliance on a single expert: Clinical subspecialists may lack scientific expertise to interpret complex findings, while pure scientists may struggle to contextualise them clinically. For example, in delayed sepsis diagnosis, a microbiologist identifies the organism, but an intensivist assesses treatment delay impact.
• Mismatched subspecialty: A general pathologist may lack granularity in neuropathology (e.g., neurodegenerative disease). Similarly, a general cardiologist may not opine on complex congenital heart disease or inherited cardiomyopathies (e.g., hypertrophic cardiomyopathy).
• Inadequate record disclosure: Scientific experts require raw data—laboratory results, imaging, or histopathological slides. Solicitors must provide all relevant records, including contemporaneous notes and specialist investigations (e.g., cardiac MRI).
• Ignoring multi-disciplinary harm: In polytrauma or complex sequelae (e.g., cardiac arrest leading to anoxic brain injury), single-expert instruction may overlook specialty interplay. Multi-disciplinary chambers provide matched experts (e.g., cardiologist, neurologist, psychiatrist) for coherent joint statements.

Expert Report Requirements

In causation disputes, expert reports must address:

• Breach of Duty: Was the standard of care met? Assess compliance with guidelines (e.g., NICE) or Bolam/Bolitho tests (Bolam v Friern Hospital Management Committee [1957]; Bolitho v City and Hackney Health Authority [1998]).
• Causation: Did the breach materially contribute to harm? Analyse scientific evidence (e.g., imaging, laboratory findings) and clinical significance. For example, in delayed cancer diagnosis, quantify staging impact on prognosis using survival curves.
• Prognosis: What is the patient’s likely trajectory with/without the breach? Include life expectancy modelling, functional impairment assessments, or psychiatric prognosis (e.g., DSM-5/ICD-11 criteria).
• Scope of Duty: Does the harm fall within the clinician’s duty? Khan v Meadows [2021] requires experts to address foreseeability of harm consequences.

Instructing solicitors should consider separate experts or dual-qualified experts (e.g., forensic pathologist with clinical experience) based on case complexity.

Practical Guidance for Instructing Solicitors

To maximise expert evidence strength:

• Identify subspecialties early: Match experts to case issues. For example, a missed spinal cord injury may require a spinal surgeon, neuroradiologist, and neurologist from a multi-disciplinary panel.
• Provide comprehensive records: Disclose all scientific data—imaging, laboratory results, or histopathological slides. In toxicology cases, include occupational health records or biological monitoring data.
• Clarify legal tests: Direct experts to address applicable causation tests (e.g., material contribution, loss of chance) and quantify breach impact. For example, in delayed stroke diagnosis, opine on likely outcome had thrombolysis been administered within the recommended window.
• Facilitate joint statements: Under CPR Part 35.14, experts must meet to narrow issues. Multi-disciplinary chambers streamline this by providing matched experts accustomed to collaboration.
• Consider inquest context: Expert evidence may need to address Article 2 ECHR obligations (e.g., systemic failures contributing to death). Brief experts on the coroner’s remit and both individual and systemic factors.

Conclusion: Strengthening Causation Through Collaboration

The Lock Review underscores the critical role of scientific evidence in causation disputes. For clinical negligence practitioners, integrating scientific and clinical expertise can determine the robustness of a causation argument. By instructing appropriate subspecialists—pathologists, radiologists, or clinical experts—and ensuring coherent, court-ready evidence, solicitors can strengthen clients’ positions in litigation, inquests, or CICA claims.

Multi-disciplinary medico-legal chambers offering matched subspecialist expertise are pivotal in complex cases, where the right consultant subspecialty determines evidence strength. Leveraging combined scientific and clinical expertise enables solicitors to navigate causation disputes with confidence.