The judge considers the expert’s reasoning alongside the claimant’s evidence, medical records, treatment history, witness accounts and the circumstances of the accident. The central questions are whether a recognised psychological condition exists, whether it was caused or materially worsened by the relevant event, how it affects the claimant and what recovery can reasonably be expected.
The Expert Assists but Does Not Decide.
Under CPR Part 35, an expert’s overriding duty is to help the court on matters within their expertise. That duty takes priority over any obligation to the claimant, defendant, solicitor or insurer responsible for the instruction or payment of the expert. Expert evidence must also be restricted to what is required to resolve the proceedings. The expert provides specialist opinion, but the judge decides the disputed facts. A psychiatrist or psychologist may diagnose a condition and express an opinion on causation, prognosis and treatment. The expert does not determine whether the claimant is legally credible, whether the claim succeeds or how much compensation should be awarded.
This distinction becomes important where a diagnosis depends on the claimant’s account. The court may accept that the expert applied an appropriate diagnostic framework while concluding that some of the factual assumptions supporting the opinion have not been established.
A Diagnosis Is the Beginning, Not the End.
A recognised diagnosis can provide an important foundation for the claim, but it does not answer every legal question.
The court will examine how the diagnosis was reached, what symptoms were identified, whether the diagnostic requirements were properly applied and whether alternative explanations were considered. A report that merely labels the claimant as having PTSD, depression or an anxiety disorder without explaining the underlying clinical reasoning may carry less weight. The court will also distinguish between a psychiatric diagnosis and ordinary emotional distress. Shock, disrupted sleep, temporary low mood or nervousness when travelling may be genuine consequences of an accident without amounting to a recognised psychiatric disorder.
The strength of the evidence depends on the expert explaining why the presentation crosses, or does not cross, the clinical threshold. The diagnosis should follow the evidence rather than being inferred from the existence of a legal claim.
The Quality of the Reasoning Matters.
Practice Direction 35 requires expert evidence to be independent, objective and uninfluenced by the pressures of litigation. Experts must consider all material facts, including those that may detract from their opinions, and must state when an issue falls outside their expertise or when the available information is insufficient to support a definite conclusion.
A persuasive report therefore shows how the expert moved from the evidence to the opinion. It should explain the claimant’s psychological baseline, the onset and development of symptoms, the diagnostic basis, the effect on functioning, the role of treatment and the reasons for the prognosis. The court may be less persuaded by an opinion that does not engage with previous mental-health problems, inconsistent reporting, unrelated life events or evidence of improvement. Ignoring evidence that complicates the conclusion can suggest that the report is incomplete or overly dependent on the claimant’s account.
A balanced report does not need to reject the claim merely because there are difficulties in the evidence. It should identify those difficulties and explain why they do or do not alter the opinion.
Medical Records Are Important but Not Conclusive.
Medical records may show whether psychological symptoms were reported soon after the event, whether treatment was sought, whether medication was prescribed and whether similar problems existed beforehand.
A long delay before symptoms appear in the records may require explanation, particularly where the claimant later describes severe difficulties from the outset. However, the absence of an early entry does not automatically prove that no symptoms existed. A claimant may initially focus on physical injuries, expect the emotional effects to settle or feel reluctant to discuss psychological difficulties.
The records must therefore be interpreted rather than treated as an infallible account. The court may consider what questions were likely to have been asked, the purpose of the appointment and whether the notes were intended to provide a complete psychological history. Repeated references to symptoms may support consistency, but repeated attendance does not by itself establish diagnosis or causation. The records form part of the wider evidential picture.
Consistency and Credibility.
Courts examine whether the claimant’s account remains broadly consistent across the medical examination, witness statement, treatment records, employment evidence and oral testimony.
Minor differences are not necessarily damaging. Recollections may vary, particularly where evidence is given years after the event. More significant discrepancies may matter where they concern the onset, severity or functional effect of the alleged condition.
For example, a claimant may report being unable to travel while records show regular long-distance journeys. That evidence does not necessarily disprove a psychological injury, because the claimant may have travelled with distress or only when necessary. The expert should investigate the apparent inconsistency rather than simply repeat either version. The court is likely to place greater weight on an opinion that distinguishes between the existence of symptoms and the degree of disability attributed to them.
Causation Must Be Separately Established.
Even where the court accepts that the claimant has a genuine psychiatric disorder, it must still decide whether the defendant’s wrongdoing caused or materially contributed to it. The expert should consider the claimant’s pre-accident psychological condition, previous treatment, medication, vulnerability and significant events occurring before and after the incident. The relevant event may have caused a new disorder, aggravated an existing condition, triggered a recurrence or accelerated symptoms that would have developed in any event.
The presence of other contributing factors does not automatically defeat the claim. Psychological conditions are often influenced by several interacting circumstances. The expert should explain the relative significance of the accident and whether the claimant would probably have experienced similar symptoms without it.
A conclusion that a disorder is “consistent with” an accident is not necessarily a complete causation opinion. Consistency means the event could explain the symptoms. The court also needs assistance on whether it did so.
Functional Evidence Can Test the Clinical Picture.
The court will examine how the alleged condition affects work, travel, relationships, domestic tasks, sleep, social activity and everyday independence.
Functional evidence may support the reported severity, but the analysis should remain careful. Continuing to work does not prove the absence of psychiatric injury, just as being absent from work does not prove that the accident caused the incapacity.
The court may compare the claimant’s reported restrictions with occupational records, social-media material, surveillance evidence or accounts from family members and colleagues. Such evidence must be interpreted in context. A short period of normal activity may not represent the claimant’s usual functioning, but a persistent pattern inconsistent with the alleged restrictions may require substantial explanation.
Competing Experts Are Compared, Not Counted.
Where the parties rely on different experts, the court does not decide the issue simply by choosing the expert with the longer report or more impressive title. It assesses the expertise, independence, factual foundation and reasoning of each opinion.
The court may permit written questions, direct experts to discuss the disputed issues and require a joint statement identifying matters of agreement and disagreement. Practice Direction 35 also permits the court to order experts from the same discipline to give evidence concurrently or on an issue-by-issue basis.
An expert who acknowledges uncertainty and fairly addresses contrary evidence may be more persuasive than one who expresses absolute conclusions unsupported by the available material.
The Court Considers the Whole Evidential Picture.
Psychological injury evidence is not assessed by diagnosis alone. The court examines whether the opinion is independent, whether the factual assumptions are reliable, whether the records support the reported course and whether alternative causes have been considered.
The strongest evidence connects diagnosis, causation, function and prognosis through clear clinical reasoning. It recognises limitations without becoming evasive and addresses inconsistencies without automatically treating them as dishonesty.
The court is not deciding whether the claimant has used the correct medical language. It is deciding whether a genuine psychological injury has been proved, what caused it and what consequences can fairly be attributed to the defendant’s conduct.
