Credible medical expert witnesses: the role, knowledge and legal obligations

Jun 21, 2017

In the first of our two-part series, we take a look at the role of medical expert witnesses, required specialised knowledge and legal responsibilities.

Providing expert evidence in any legal proceeding is a professional privilege. Doctors can play an important role as expert witnesses in helping courts, tribunals or other dispute resolution processes make informed, fair decisions on cases involving clinical issues. A dearth of expert witnesses in Australia, means doctors who are able to provide impartial and credible expert opinions are in demand. ­­

Expert witnesses: there’s a difference

There are different types of expert witnesses. These include evidence sought as a witness of fact (the treating doctor) or as a witness of opinion (the independent expert witness). Sometimes a doctor may be asked to fulfil both roles, for example, to describe a bruise seen as a treating doctor (factual evidence), and then be asked for an opinion as to the time the bruise may have been present (expert evidence).

The capacity in which you are asked for an opinion may not always be clear from a solicitor’s letter. Look for any references to the court’s ‘Expert Witness Code of Conduct’ as this may be an indication that you are being asked to provide evidence or a report as an expert as opposed to a treating doctor or a witness of fact.

When are expert witnesses used?

When it comes to courts and disciplinary matters, expert witnesses are usually called upon to give evidence in three situations:

1.In a civil case an expert witness will be asked to give their opinion about whether the doctor acted in accordance with the accepted standard of care with knowledge that was available to the doctor at the time, or whether any departure from the standard of care led to the harm suffered.

2.In cases where a doctor faces a disciplinary body, the expert witness will be asked to give their opinion about whether the doctor has acted either below or in line with the peer standard for their level of experience.

3.Less frequently, an expert may be engaged during a coronial inquest to assist the coroner to decide on the cause of death, and what role any individual or institution may have played in that death.

Understanding the role of legal proof

An important part of being an effective expert witness is understanding the difference between scientific proof and legal proof. In any legal proceedings, the court must make a decision which is based on the facts and opinions before it. Courts cannot sit on the fence, and court decisions need not be based on scientific certainty. Doctors are trained to apply scientific certainty as the standard of proof. In comparison, legal proof is based on the balance of probabilities (more likely than not) in civil cases, and beyond reasonable doubt in criminal matters. The courts themselves have recognised that the disciplines do not always share the same approach. One judge described it as ‘law marching with medicine, but in the rear and limping a little.’

What does it take to be an expert witness?

The expert’s role

An expert witness must have specialised knowledge and skills based on their training, study or experience that is relevant to the matter at hand. Expert witnesses are also required to demonstrate to the court that their opinion expressed in evidence “is wholly or substantially based on that knowledge.”2

Legal obligations and mindset

Doctors acting as expert witnesses have an important duty in the legal system. It is not up to the expert witness to decide on the facts, as in what and how something happened. Neither is it up to the expert witness to decide on whether a doctor or party is ‘negligent’.

Most state and territories have an Expert Witness Code of Conduct or guidelines, which outline the requirements for expert evidence. It is important to obtain a copy of the relevant code when preparing a report.

In summary, expert witnesses should3:

  • Provide independent evidence to the court which is not influenced in terms of its form or content by the rigours of litigation.
  • Assist the court by giving an objective and unbiased opinion in relation to matters within their expertise.
  • Never assume the role of an advocate.
  • State the facts or assumption upon which their opinion is based and not omit to consider material facts which could detract from their conclusion.
  • Make it clear when a particular question or issue falls outside his expertise.
  • State their opinion is no more than a provisional one, if they consider that there is insufficient data available to form an educated opinion. In cases where an expert witness has prepared a report but cannot assert that the report contained the truth, the whole truth and nothing but the truth without some qualification, this needs to be stated in the report.
  • Communicate if they have changed their view on a material matter, for example, after reading the other side’s expert’s report. This should be communicated through legal representatives to the other side without delay and when appropriate, to the court.

Experts also represent their professional colleagues in defining the acceptable standard of care. Therefore, it’s important that the expert correctly understands the range of acceptable practice and recognises that although they might have taken a different approach, this should not influence whether the practice was in accordance with the appropriate legal duty of care.

Making the time

If you are considering becoming an expert witness, it’s also important to have enough time to fulfil your duties. Thinking you can read a brief and provide an opinion in your ‘spare time’ may be overly optimistic, however these tips should help:

  • Medico-legal reports take time and they should not be rushed
  • Devote a portion of your working week to carrying out work as an expert witness
  • Do not take shortcuts
  • If you do not have the time to perform the work in the agreed time frame, ­­ say so. The legal team may be able to ask for more time.

Breadth of expertise

Should you decide to become an expert witness, it’s also a good idea to perform  work for both ‘sides’ – in civil cases, for the plaintiff and defendant, and in disciplinary matters for the regulator and the defence team – to gain a breadth of experience.

More information

The Whole Truth Handbook: responsibilities when providing evidence can assist doctors in giving evidence in court. Complete the course material and receive a certificate of completion and CPD points.

Download the AMA’s Ethical Guidelines for Doctors acting as Medical Witnesses 2011. Revised 2016.

Look out for part two in our series on expert witnesses in your July Avant Newsletter. Part two will look at the medico-legal implications of being an expert witness including key tips and traps and an illustrative case. 


1 Mt Isa Mines Ltd v Pusey (1975) 125 CLR 283 at 395

2 Dasreef Pty Limited v Hawchar [2011] HCA 21

3James v Keogh (2008) SASC 156.

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