Medical expert witness in court Francesca M Brett MD., FRCPath., FFPath., Msc (FM ). Background Key element of the law of evidence is that : Witnesses allowed to give relevant and factual evidence ( not allowed to express opinion )
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Medical expert witness in court
Francesca M Brett MD., FRCPath., FFPath., Msc (FM)
Unlikely that either the Judge or Jury in serious cases will possess the expertise
necessary to determine complex issue such as DNA evidence etc.
Expert witnesses and expert evidence form an important part of criminal and civil trials
“ It is a long established rule of our law of evidence that with certain exceptions,
a witness may not express an opinion as to the fact in issue.. It is for the tribunal of
fact – judge or jury as the case may be – to draw inferences of fact, form opinions,
and come to conclusions”
AG (Ruddy) v Kenny (1960) 941. L.T.R.
Expert witness is the exception – an opinion can be given by a witness
who has expertise in an area that is relevant to the issue at hand
It must be shown that the expert witness is necessary and relevant
That the witness is a qualified expert.
The main role and function of the expert is “to furnish the judge or jury with
the necessary scientific criteria for testing the accuracy of their conclusions, so
as to enable the judge or jury to form their own independent judgement by the
application of these criteria to facts provided in evidence”.
Per Lord President Cooper in Davie v Edinburg Magistrates  SLT 54
R v Turner  1 QB 834
“ If on the proven facts a judge or jury can form their own conclusions without help,
then the opinion of an expert is unnecessary. In such a case, if it is given dressed up in
scientific jargon, it may make the judgement more difficult. The fact that an expert
witness has impressive scientific qualifications does not by that fact alone make
his opinion of matters of human nature and behaviour within the realms of normality
any more helpful than that of the jurors themselves; but there is a danger that they
may think it does”
Expert evidence presented to the Court
should . ..
1. Be the independent product of the expert uninfluenced as to the form or content of legislation
2. Provide an independent unbiased assistance.
3. State the facts and assumptions and not omit material facts that could
detract from concluded opinion.
4. Make it clear when a question or issues falls outside area of expertise
5. Be properly researched and if not state that
6. Communicate to the other sideany change of view that occurs after exchange of reports
7. Provide the evidence such as photographs etc to the opposite side at the same time as exchange of reports
Head injury in children – complex and frequently raises the question of abuse
Main question – “Is the injury consistent with the story”?
“ The clinical history is perhaps the single most important clinical tool available to clinicians and to reject the carer’s version of events in favour of another requires the highest possible level of medical evidence. After all, the Doctor is effectively accusing the carer of lying”
R v Lorraine Harris, Raymond Charles Rock, Alan Barry, Joseph Cherry, MichaelIan Foulder. Supreme Court of
Judicature Court of Appeal (Criminal Division). July 2005
Picture of child abuse complex but 3 factors are thought to lead to increased risk
Child factors – behavioural problems
Parental factors – mental health problems, alcohol or drug addiction
Socio-situational - single parent, new partner, unemplyoment
What is Shaken Baby Syndrome ???
Accepted definition depends on a triad of encephalopathy, subdural and retinal haemorrhages
The phrase ‘Shaken Baby Syndrome’
evokes a powerful image of abuse, in which the carer shakes the child sufficiently to cause whiplash forces resulting in subdural and retinal bleeding
Shaken Baby Syndrome is an area where the opportunity
for scientific experimentation and controlled trials do not exist but in
which much rests on the interpretation of medical evidence
In short we don’t know how much force is necessary to injure an
Unfortunately people have been convicted of murder in cases of suspected SBS
In the recent highly-publicised case of R v. Sally Clark, a medical expert witness drew on published studies to obtain a figure for the frequency of sudden infant death syndrome (SIDS, or "cot death") in families having some of the characteristics of the defendant's family. He went on to square this figure to
obtain a value of 1 in 73 million for the frequency of two cases of SIDS in such a family.
"This approach is, in general, statistically invalid. It would only be valid if SIDS cases arose independently within families, an assumption that would need to be justified empirically. Not only was no such empirical justification provided in the case, but there are very strong a priori reasons for supposing that the assumption will be false. There may well be unknown genetic or environmental
factors that predispose families to SIDS, so that a second case within the family becomes much more likely.
Society does not tolerate doctors making serious clinical errors because it is widely understood that such errors could mean the difference between life and death. The case of R v. Sally Clark is one example of a medical expert witness making a serious statistical error, one which may have had a profound effect on the outcome of the case.
The Royal Statistical Society
23 October 2001
Daubert v Merrell Dow Pharmaceuticals,Inc 1993
Standard for expert evidence within the scientific community should rest on both a reliable foundation and be relevant to the task at hand
~ Whether the theory or techniques had been or can be tested ?
~ Whether it has been subject to peer review and publication?
~ What is the known of potential error rate?
~ The existence and maintainence of any standards controlling its operation?
~ Whether it has attracted widespread acceptance within the relevant scientific community?