The Role of the Expert Witness and Considerations when Writing an Expert Report

Jennifer Dobson BSc(Hons) CCAB


Reproduced by kind permission from Veterinary times; First published in Veterinary Times Vol 41-14 dated 11th April 2011

Some Court cases require very precise, detailed expertise of specific areas which may be beyond the knowledge of the Court, requiring the use of an Expert Witness. The British Veterinary Forensic and Law Association (BVFLA) recognises this role and runs training days and seminars, sometimes in association with the Academy of Experts,  to train and inform Veterinary Surgeons and others undertaking this work, some of which has helped to inform this article.


What is an expert? 


In England and Wales the judge decides who is an expert. It is for the expert to present evidence, in terms of a CV or Certificate of Competence to Comment, to convince the Court that he/she is a valid expert in that field (in civil cases the Court needs to give permission to use an expert).


According to the R.C.V.S guidance “An expert is anyone with knowledge or experience of a particular field or discipline beyond what is expected of a layman.” but in court someone presenting themselves as an expert on veterinary matters would be expected to be a registered Veterinary Surgeon of good standing.


However as an Expert witness it would also be relevant as to how well that expertise of the relevant subject can be used in a legal role – taking up references, writing a good report,  answering  cross examination well, examining opposing evidence thoroughly and ensuring you behaved as the Court would wish, including disclosure and impartiality.


j dobson art 5 fig 1 dorking crt bvfla compr

fig 1  

If they met the criteria those wishing to be considered for expert witness work can apply for membership of an Expert’s Register, such as the Academy of Experts.


Why are Expert Witnesses Needed?


The British judiciary system is an adversarial one and the judge may not entirely understand the issues in each case. In such cases it is down to the expert(s) to assist the court in these areas. To this end it is the responsibility of the expert to use language appropriate to the audience that can be understood by a lay bench or judge, rather than using professional jargon.


Although an Expert Witness is generally instructed by one side or the other, their duty is to the court, not to either side in the case (nor to a patient or to a client) and they must not have  a vested interest in the outcome of the case, i.e. they cannot work on  a no-win, no-fee basis.


However there can be differences of opinion amongst experts and it is in the nature of this adversarial system that those presenting themselves as Experts must accordingly expect their evidence and their impartiality to be tested.


If you cannot deal with criticism you should very carefully consider whether you are suited to this work as, however well you do your report, criticism from lawyers is to be expected and is part and parcel of the lawyers doing their job.  However if there is any judicial criticism of an Expert this is required to be disclosed at future cases (Rich 2010) with proper disclosure being a highly important part of being an Expert Witness.


If judicial criticism were not disclosed but was discovered this could cause the witness to be dismissed and may contribute to a “bad character” judgement. This would be the worst possible judicial criticism and would be if a person’s behaviour was criminal, negligent, or so reprehensible or so blatantly biased that the person should never appear in court again as a witness.


Cross Examination

It is not the expert’s problem if those instructing them, the judge or the court don’t like their opinion, so long as it is their honestly-held and substantiated opinion.  If the other side are trying to get a witness ruled out it implies that the witness has something damaging to say, as faulty evidence can rightly be attacked in court. 

Attacking an expert’s background can be a technique to prevent evidence being heard.  If your credentials, possibly including your integrity, your impartiality and your honesty, are attacked it could be implied there is not much in your report that they can attack.  In that sense it could be seen as a compliment. It does not mean someone is not an expert.

Most cross examination is about finding something to undermine.  Different lawyers have different styles of cross examination and both closed and leading questions may be asked, for different purposes, or by different sides.

One barrister, Jonathan Rich, considers that humour is one of his tools and a powerful device, with people remembering the barb in the joke. He believes cross examination is best done in a sensible academic matter, and not done crossly, joking that “Up the judge’s nose is not the way to the judge’s brain”.


The Bar Council has a Code of Conduct of allowable and non-allowable questions, irrespective of clients’ instructions.  There must be reliable evidence to make any allegations such as lying e.g. using information from a whistleblower could be difficult to prove.  Sometimes the best way to deal with an allegation is to ask for the particulars (Rich 2010).


Bias doesn’t stop evidence being heard but if demonstrated, will reduce the weight given to the evidence, possibly to nil.  It is for the judiciary to compare and contrast the weight of evidence to decide which version they find most convincing. Some may consider that an Expert Witness who regularly only gives evidence for one side may not be a genuinely impartial Expert


The Expert Report, Three I’s, Three R’s.


There can be problems when presenting evidence where much knowledge is covered simply by common sense knowledge of animal welfare that may not always be well referenced in the scientific literature. Conversely you sometimes know something is poor science but you may lack scientific papers for backup to prove your view. 


You should also be aware of opposing evidence drawn from inappropriate comparisons, for example directly extrapolating the alleged effects on dogs of exposure to ammonia fumes using scientific guidance for effects in humans, without regard for the different susceptibility of dogs, or the effects of acclimatisation (Vogel 2010).


Using  “The Three ‘I’s”, namely Independence, Impartiality and Integrity can avoid justified criticism of the expert’s evidence and report and following these guidelines makes objectivity a given, otherwise  there can be the risk of someone being a “hired gun”, aiming at whoever they are paid to attack. (Cohen 2010).


It is possible that the correct objectivity resulting from using these rules may result in the evidence produced not being what may be wanted by those instructing, or that is not liked by the bench, but honest opinion, “without fear or favour” should always be what expert evidence is based on, and is what best stands up to cross examination, as there is nothing being hidden to be caught out on.


When considering evidence is it is also important to remember the three R’s; Reveal, Record, Retain (Cohen 2010).


On the prosecution side everything must be revealed and failure to disclose documents on the prosecution side is indefensible.  If you forgot them you are inefficient, if you ignore them, or accepted hearsay evidence from someone, it implies, at best, that you were not rigorous enough (Rich 2010).


Recording everything may also include informal chats. Anything that is not recorded and retained cannot be proven. Ensure you have good quality control for lab tests and continuity.


Experts should take care not to move beyond their area of expertise, possibly due to idealism, or inexperience when enticed by a desire to be helpful when questioned in court. It may not always be the bulk of the facts that are disputed but the interpretations of those same facts (Newbury 2010). For example what is proper, or “propriety” is in the eye of the beholder e.g. is something such as penning animals normal farm practice or cruelty? (Rich 2010)


Dramas and games are played in court as part of the lawyers’ art but whilst respecting the court, you should not be intimidated by it, so you can say no, or appeal to the bench, or explain that the requested “black or white answer” (closed question technique) could mislead the court by not giving the full picture, remembering that the solicitor and barrister are there to challenge you (Newbury 2010). 


Part of the job of an Expert Witness is like an auditor, checking the technical information provided to the Court, checking that all the possible interpretations of differential diagnosis and options had been explored.  Someone may not have lied, but may not have told the whole story.  Is the opinion based on scientific fact?  Is it provable or is it opinion based on general consensus of the profession, without definitive evidence available?  You need to produce a good report that separates points of fact from points of opinion and which comes to a conclusion, based on the instructions given.  It is not for you to interpret the instructions.


Once completed and before signed off, every word in the report should be very carefully checked, with the three I’s and the three R’s in mind. Once signed off the report is an official document and is set in stone, even if it’s never seen again.  You cannot just go back and tweak or reconsider something sometime later. Any typographical or factual errors that do come to light should be identified and addressed as soon as possible, but factual errors may be used attack the strength and credibility of the remaining sections of the report.



j dobson art 5 fig 2 record keeping copy

 fig 2 

If you do a good report it may mean the case doesn’t go to court, while standing you in good stead if it does.


Single joint experts


Experts can undergo training as a “Single Joint Expert” and in some civil cases a Single Joint Expert may be appointed whose findings all parties agree to accept, although each side may put different questions, seeking to have the outcome focus on features of the case more favourable to them.


Criminal cases have a much wider scope for a disastrous outcome, with reputation, liberty, family life and livelihood all being at risk, so there is usually too much distrust in the criminal court for a Single Joint Expert to act in the same way as in civil cases.


To save court time courts will sometimes instruct opposing Expert Witnesses to have an expert meeting prior to the court case, to iron out as many differences as they can, to reach agreement on as many points as they can and to identify remaining points of difference.


If the case does go to court it is part of the role of the Expert Witness, unlike the Professional Witness, to sit behind the instructing lawyer in order to assist live in court with any technical aspects of the expert areas, when required.


Conflict of interest, Professional and Expert Witnesses


Experts should aim to avoid conflicts of interest where possible, such as being a witness of fact and being an expert, or being employed in another capacity by one side or the other. If employed by the side they are acting for, such as being the defendant’s registered Vet while also being the defence Expert Witness, impartiality may be perceived to be compromised, or if acting on the opposing side while being the defendant’s registered vet it may be perceived that the expert is going too far the other way to over-compensate.


Evidence from a witness could be disallowed for failure to disclose a possible conflict of interest, e.g. having been an employee in the past for one side, or having acted as a veterinary surgeon in the past for a member of the bench hearing the case, even though that conflict itself may not have been a problem per se, nor caused the evidence to be disallowed, had it not been declared.


Evidence of Expert training, such organised and conducted by BVFLA, can be very helpful to prove awareness of the requirement for impartiality and to help demonstrate independence as an Expert Witness, e.g. if someone is employed in their veterinary capacity and is not available on the open market. In these cases a CPS declaration should be completed, along with a declaration of any judicial criticism, to avoid any opportunity for attack on those circumstances.


As explained in the RCVS’s “Guidance to Veterinary Surgeons and Veterinary Nurses Giving Evidence in Court” there can be a conflict of interest if the Vet involved at seizure is also the Expert witness, particularly if they are also the Vet treating the seized animal. In such a situation it may be more appropriate for that vet to be a Professional Witness, i.e. a professional who is a witness giving evidence of fact, rather than an expert. A Professional Witness should be restricted to matters of fact not opinion, but in practice things do not always have perfect separation between Professional and Expert Witnesses.


For example in some cases a vet may be a witness of fact, being present at the scene and collecting their own samples, to enable their expert opinion to be given later, based on those sample results. In such cases the underpinning facts can be used to establish your expert opinion, in which case you must sign an expert declaration. 


Wasted Costs


Expert Witnesses are required to adhere to the instructions given and the specific questions asked, not those they may wish had been given, nor those they may think should have been given.


If a judge considers an expert has been flouting rules, such as ignoring the instructions given (rather than just giving poor evidence), or if there has been wasting time such as not previously disclosing new areas that come up during evidence, “wasted costs”  can be given which can be for hundreds of thousands of pounds (Cohen 2010).


It is intended to be a personal penalty and so is given against the person, not the firm, it cannot be passed on to the client, it cannot usually be insured against, nor can it be claimed against expenses as it is essentially a penalty fine (Cohen 2010).


Another reason to ensure you exercise honesty, integrity, independence, impartiality, disclosure, good continuity and good  record keeping in all and any expert work you undertake.



Images & captions:


fig 1 (Dorking Magistrates Court) caption: An Expert Witness may be required to appear in Court to assist the Court with specialist expertise.


 fig 2 (Record keeping items) caption: Accurate and detailed record keeping including sample taking, labelling and continuity is a very important aspect of  all forensic work





Cohen, M (2010) Crossing the line: when is judicial criticism of experts justified?  Unpublished lecture

                  notes B.V.F.L.A Conference, Held at The Academy of Experts, London 27.10.2010


Newbery, S.G. (2010) Avoiding criticism of your report and evidence Unpublished lecture notes B.V.F.L.A

                 Conference, Held at The Academy of Experts, London 27.10.2010


Rich, J (2010) Proper cross examination of experts and judicial treatment Unpublished lecture

                  notes B.V.F.L.A Conference, Held at The Academy of Experts, London 27.10.2010


Vogel, C (2010) Campaigns of criticism-when do they happened and why?  What can be done to

               counter them?  Unpublished lecture notes B.V.F.L.A Conference, Held at The Academy

              of Experts, London 27.10.2010



Last Updated (Thursday, 26 May 2011 17:54)

Search Content
Member Login