To Be or Not To Be... an Expert Witness

To Be or Not To Be… an Expert Witness

To Be or Not To Be… an Expert Witness


In all developed systems of law, the evidence of expert witnesses can be crucial to the outcome of a dispute. Nowhere is this more so than in the UK, where expert evidence has been used in court cases since at least the 15th century. Nowadays it may be required in civil, family and criminal proceedings, as well as in arbitrations, before specialist tribunals, and for public or parliamentary inquiries.


Experts and expert witnesses

An expert is anyone with knowledge or experience of a particular field or discipline beyond that to be expected of a layman. An expert witness is an expert who makes this knowledge and experience available to a court to help it understand the issues of a case and thereby reach a sound and just decision. There is, currently, no precondition imposed by English law on the qualities required of an expert witness. It is for the courts, on a case by case basis, to make a judgment of the individual’s qualities and to weigh the expert’s evidence in accordance with this judgment.


What is expert evidence?

The fundamental characteristic of expert evidence is that it is opinion evidence. Good quality expert evidence must provide as much detail as is necessary to allow the judge to determine that the expert’s opinions are well founded. It follows, then, that it will often include:

  • factual evidence obtained by the witness which requires expertise in its interpretation and presentation;
  • factual evidence which, while it may not require expertise for its comprehension, is inextricably linked to evidence that does;
  • explanations of technical terms or topics, as well as,
  • opinions based on facts adduced in the case.


Duties of an expert witness

The overriding duty of an expert witness is to the court – to be truthful as to fact, thorough in technical reasoning, honest as to opinion and complete in the coverage of relevant matters. This applies to written reports as much as to evidence given in court. At the same time, the expert assumes a responsibility to the client to exercise due care with regard to the investigations carried out and to provide opinion evidence that is soundly based.

To fulfil these duties adequately, it is vital that the expert should also have:

  • kept up to date with current thinking and developments in his or her field, and
  • familiarity with the provisions of the various civil, family or criminal court rules.


Qualities required of an expert witness

Expert evidence should be – and should be seen to be – independent, objective and unbiased. In particular, an expert witness must not be biased towards the party responsible for paying the bills. An expert’s evidence should be the same regardless of who is paying for it.

Clearly, too, an expert witness should have:

  • a sound knowledge of the subject matter in dispute, and, usually, practical experience of it;
  • the powers of analytical reasoning required to fulfil the assignment;
  • the ability to communicate findings and opinions clearly and concisely;
  • the flexibility of mind to modify opinions in the light of fresh evidence or counter-arguments;
  • the ability to ‘think on one’s feet’, especially important on those rare occasions one is faced with cross examination, and
  • a demeanour that is likely to inspire confidence, particularly in court appearances.

Lastly, an expert should be wary of expressing any opinion on allegations of negligence on the part of anyone, professional or otherwise, who may be involved in a dispute. The opinions given should relate solely to the facts of the case: it is for others to apportion blame.


The fees experts charge are, in large part, market driven. What’s more, fees charged in cases that are paid for from public funds are subject to Ministry of Justice caps. This means they are around half those charged habitually in civil cases. The UK Register of Expert Witnesses conducts a biannual survey on expert fees (next survey due summer 2017) amongst its members. Its current average hourly report writing rates for non-legal aid work (2015 data) are:


Professional group


Report writing (£/hour)
Medicine (n = 198)


Paramedicine (n = 51)


Engineering (n = 51)


Accountancy & Banking (n = 27)


Science & Agriculture (n = 30)


Surveying & Valuation (n = 20) 188
Architecture & Building (n = 23)





Expert witness work can be a rewarding adjunct, both intellectually and financially, to an existing professional workload. However, anyone considering entering the fray should take care to understand the nature of the role and the expert’s duties and ethical considerations therein.


About the author

Dr Chris Pamplin has been Editor of the UK Register of Expert Witnesses since its start in 1988. Most of his time is now spent on the professional support and education of expert witnesses. He is a regular contributor to meetings and publications that consider aspects of expert evidence in the UK.

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