Expert witnesses: stuck between the courts and the GMC
BMJ 2017; 357 doi: https://doi.org/10.1136/bmj.j2034 (Published 04 May 2017) Cite this as: BMJ 2017;357:j2034
- Michael J Powers, QC, fellow of the faculty of forensic and legal medicine
- powersqc{at}icloud.com
Decisions about the reliability of all expert witnesses should be left to the courts, but the General Medical Council currently exercises an unacceptable level of control over medical expert witnesses. The problem was highlighted in the recent case of the paediatric neuropathologist Waney Squier.1 Shaken baby syndrome describes a hypothesis to explain a triad of thin layer subdural haematomata, retinal haemorrhages, and encephalopathy in babies whose carers are being investigated for possibly inflicting intentional injury. Most doctors prepared to give evidence on the syndrome believe in the hypothesis, although there is little or no scientific support for this belief.2 Whereas it is the scientist’s duty to attempt to prove even popular hypotheses wrong, danger awaits any doctor challenging majority opinion when it comes to shaken baby syndrome.
Squier was struck off the Medical Register for dishonestly giving evidence in cases of alleged shaken baby syndrome after she expressed doubt that the forces from shaking were sufficient to cause the syndrome. A panel of the Medical Practitioner Tribunal Service found she had dishonestly gone beyond her expertise. The High Court on appeal quashed the finding of dishonesty on the charges brought by the GMC and restored her name to the register.3
Other medical experts in the cases reviewed in the Squier case were not similarly censured for saying that the forces of shaking are sufficient to cause the triad, although such biomechanical evidence was beyond their expertise too. Similarly, neuropathologists and neurosurgeons could say without any fear of GMC censure that the forces resulting from low level falls are insufficient to cause the syndrome, but medical experts expressing doubts about this view risk a GMC charge that they have gone beyond their expertise by giving biomechanical evidence.
In its guidance to doctors, the GMC says that experts must give expert testimony and opinions only about matters that are within their professional competence or about which they have relevant knowledge.4
Circular argument
Those who transgress the boundary of expertise but stay with the conventional view are unlikely to attract GMC scrutiny or censure. The logic seems to be that an “acceptable” opinion emanates from a relevant knowledge base, whereas an “unacceptable” opinion does not. An expert who does not have that relevant knowledge is therefore outside his or her expertise.
Notwithstanding that “the boundary line between a proper explanation of support or doubt and trespassing impermissibly outside the expertise of the witness is imprecise and difficult to identify in any particular case,”1 the GMC effectively uses the threat of disciplinary proceedings to control both who can provide evidence and the content of the opinion itself. A complaint to the GMC that a doctor has given evidence outside his or her expertise will result in scrutiny of court transcripts. How can an expert with “relevant knowledge” not agree with majority opinion? Experts expressing a minority opinion either do not have relevant knowledge or the opinion is otherwise beyond their expertise. Unconventional opinions are therefore more likely to be deemed over the boundary line that the GMC chooses to set.
The court controls the admissibility of expert evidence through well established rules and criteria. Opinion evidence is confined to matters within the expertise of the expert. Whether evidence is “expert” or not is a matter of fact for the court to determine—although it may not be able to determine the range and depth of expertise without hearing the evidence of other experts.
In the criminal courts it is spelt out that when considering the reliability of expert scientific opinion, the court should be on the alert for flaws detracting from its reliability.5 Red flags would include experts espousing a hypothesis that has not been subjected to sufficient scrutiny (including, where appropriate, experimental or other testing) or that has failed to stand up to scrutiny. Like scientists, the court has a duty to ensure hypotheses are thoroughly challenged before placing any reliance on them; without scientific foundation one hypothesis is as good (or useless) as another.
Experts, medical or other, failing in their responsibilities will find themselves censured by the court and their evidence dismissed.
Although lay members now comprise the majority of GMC disciplinary tribunal panels, the dictum of the Court of Appeal in 2006 that the court should decide who qualifies as an expert in a given area remains good. The appellate court would have to accord due deference to the evaluation of a panel substantially composed of doctors for the obvious reason that they are better placed to make a peer judgment when the charge before the panel relates to clinical work. But when the only charge relates to the doctor’s evidence given during legal proceedings there is no similar foundation for deference. It is the judges who set the standards that they require of the expert witnesses appearing before them, and it is they who are best placed to evaluate whether and to what extent an expert witness falls below those standards.6
The GMC’s interest in controlling expert witnesses is resulting in fewer doctors coming forward to assist the courts when doing so places them at risk of GMC action. As the Squier case shows, this is having an adverse impact on the administration of justice. Save for wholly exceptional cases, the GMC should leave the question of whether an expert has transgressed the boundary line of his or her expertise to the court in which the evidence is given.
Footnotes
Competing interests: I have read and understood BMJ policy on declaration of interests and have no relevant interests to declare.
Provenance and peer review: Commissioned, not externally peer reviewed.