Medical testimony in criminal cases needs reform

Concerns about the role of expert evidence in criminal trials centre on ensuring that judges and juries hear a fair and balanced interpretation of complex, nuanced, and uncertain medical evidence in the UK’s adversarial legal system. Currently, there is no adequate assurance that appropriate experts will be engaged by either legal team, nor that their testimony will be scientifically or statistically sound. There is an urgent need to reform the system of medical expert testimony to avoid miscarriages of justice.12

The UK lacks formal regulation of medical expert witnesses. There is no statutory register, no mandated peer review of the evidence submitted in court, and no oversight from royal colleges. Although the General Medical Council offers guidance on providing expert evidence, it is largely up to individual doctors to decide if they are qualified to act as an expert, subject ultimately to the court’s control.2 Courts may approve doctors who would not be considered experts by their peers or who have long since retired and lack current understanding of the specialty areas they are analysing.34

The adversarial structure of our legal system creates strong incentives for “expert shopping”—seeking out those willing to frame opinions in support of a particular narrative. Although experts are formally required to provide impartial evidence, they are often not held accountable if they fail to do so. This dynamic allows some experts to provide opinions aligned with the interests of the instructing party.56 Many excellent clinicians that we have spoken to, who would be suitable experts, choose to avoid working in the criminal justice system, citing concerns about scientific integrity.

Historically, miscarriages of justice have arisen from the misuse of statistics and unreliable medical expert testimony. The wrongful conviction of Sally Clark for the murder of her two sons is a striking example. The conviction relied on statistically inaccurate claims by Roy Meadow, a professor of paediatrics.78 After this case, courts and judges—often ill equipped to evaluate statistical and scientific validity—relied on the discredited “Meadow’s law,” allowing similarly flawed testimony in other trials.9

In 2016, barrister Ben Myers, who later defended Lucy Letby, coauthored a report for Justice, an all party campaign organisation.10 The report recommended that joint expert reports be prepared before trial proceedings. This would require experts from both the prosecution and defence teams to collaborate, clearly outlining areas of agreement and disagreement with supporting evidence. Where experts largely concur, their presence on the stand might be unnecessary, potentially reducing trial length, cost, and risk of bias. In cases of substantial disagreement, the court would benefit from a clear written record of expert divergences before testimony.10

But this system still depends on both parties having access to appropriately qualified experts. A fairer approach would ensure that both sides have access to suitably qualified medical experts from the outset, allowing a more balanced evaluation of evidence.1112

Calls for reform of the rules governing expert medical evidence are not new. In 2011, the Law Commission recommended stricter admissibility criteria for expert evidence in criminal trials, but those proposals were never adopted.13 Reform is needed: a register of expert witnesses, with proper clarity about their disciplines, regulated and maintained by professional medical bodies. In our view, multidisciplinary panels rather than lone experts should be instructed in complex cases. For highly complex clinical cases, we think that an inquisitorial approach—where the judge actively investigates the evidence rather than relying solely on adversarial contest—may provide a more reliable framework than the current system.