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Dealing with possible criminal cases: witness work
  1. James Yeates


Vets play an important role in providing evidence to courts on cases of animal cruelty and abuse. In this article, the second in a series on being involved in potential criminal animal welfare cases, James Yeates discusses the important aspects for vets to consider when acting as veterinary witnesses, either by providing factual testimony or expert opinion to courts, for cases of animal cruelty.

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Embedded ImageJames Yeates qualified from Bristol university in 2004. He is now chief veterinary officer of the RSPCA, an RCVS Specialist in animal welfare science, ethics and law and a fellow of the RCVS.

WITH possible animal cruelty cases, after the forensic work, if the prosecuting authority decides that there is sufficient evidence and public interest in proceeding, you may be asked to provide witness testimony.

This article, the second in a series on being involved in potential criminal animal welfare cases, will focus on the general principles that vets should consider when acting as witnesses in court cases relating to animal cruelty. The series is intended to be read before being involved in a case, alongside guidance from the RCVS and Crown Prosecution Service and other sources of advice.

Types of veterinary testimony

Veterinary surgeons can be useful to the court in two ways: to provide facts and to provide opinion.

The first is to provide factual information as evidence. Occasionally, this evidence is not veterinary (eg, if a vet witnesses someone punching another person in their car park). More often, this evidence relates specifically to their own findings regarding veterinary matters, such as the information obtained during clinical and forensic casework.

Box 1:

Duties and responsibilities of expert witnesses*

■ Expert evidence should clearly be the independent product of the expert uninfluenced as to form or content by the exigencies of litigation

■ Provide independent assistance to the court by way of objective unbiased opinion in relation to matters within your expertise. Never assume the role of an advocate

■ State the facts or assumption upon which your opinion is based. Consider all materials that could detract from the concluded opinion

■ Make it clear when a particular question or issue falls outside your area of expertise

■ Indicate if the opinion is a provisional one if there is insufficient data available. State any qualification if you cannot assert that the report contains the whole truth and nothing but the truth

■ If you can change your view, communicate that change (through legal representatives) to the other side

■ Provide any relevant photographs, plans, calculations, analyses, measurements and such to the opposite party when reports are exchanged

* after National Justice Compania Naviera SA v Prudential Assurance Company Limited, (known as the ‘Ikarian Reefer’ case) (1993)

The second is to provide opinions. Magistrates and judges are rarely qualified veterinary surgeons. In some cases, a court may be able to reach a conclusion without veterinary assistance; for example, by referring to codes of good practice or in cases involving witnessed beatings. In other cases, the court may require additional expertise that goes beyond the facts of the case to assist them in reaching a decision; in these instances, the professional expert opinions of a vet may be needed. For example, veterinary professionals may be able to give the court an opinion on whether an animal (is likely to have) suffered and the duration and severity of that suffering.

Although you can not really refuse to be a witness of fact if the court needs you to, usually you can choose whether to give an expert opinion. However, giving expert opinions should be considered as an important part of ensuring justice and protecting animals, so you should not decline for reasons purely of self-interest. Nor should you be nervous about giving an opinion, so long as it is within your competence – that is what the courts want and need from you. Additional training and experience is not necessary for witness work (often newly qualified vets are excellent experts), although formal/informal training on report writing and courtroom presentation can be very useful. If you are not prepared to act as an expert witness or to go to court, you should make this clear from the outset. If another veterinary surgeon is likely to give an opinion, they may well be willing to act as an advisor on what evidence they would consider useful, thereby improving one's confidence.

Giving factual testimony

Veterinary professionals may be witnesses of several observable ‘facts’. This involves their personal observations (eg, their clinical examination or observations of the animal's behaviour) and facts about their investigation (eg, tests performed). In some cases, such tests and observations involves some professional judgement (eg, judging a skin colour or in scoring an animal's condition using an objective scoring system).

Opinions about the case should be based on principles of animal welfare science, where determining suffering involves a consideration of the animal's circumstances, its physical and pathological states and/or the animal's responses

A veterinary professional must provide all of the relevant facts that they know first hand. Facts that might be relevant should not be omitted. Only the facts that are known personally should be provided. For example, a veterinary surgeon may know that they took a blood sample from dog C on date D, labelled it as L with tamper-proof measures M, sent it to accredited laboratory A and got back result R. Keeping clear records such as these avoids veterinary professionals reporting on matters they did not observe, such as the testing procedure at the accredited laboratory, while still providing relevant information. It is then up to the court to decide whether they require testimony from the laboratory technicians.

Giving expert opinions

Veterinary professionals can provide opinion to the court on specialist or technical matters within their own particular expertise. The central principle is that you are there to assist the court. This places the veterinary surgeon under certain responsibilities (Box 1).

Matters on which opinions might be given

As an expert you may be asked to give an opinion on ‘animal matters’, such as whether and how much an animal suffered. These can help the court to answer particular questions about the guilt of the defendant, which is for the court (and not the expert) to decide. You should also ensure that you understand exactly what questions you are being asked to answer. If your instructions are unclear, you should ask those instructing you to explain them further. If the instructions are still not clear, it may be better not to provide any expert opinion.

For example, a veterinary surgeon does not need to give an opinion on whether a person has caused unnecessary suffering (and such an opinion may be ignored or rejected by the court), but there may be matters within the veterinary surgeon's expertise that could help the court in judging necessity (Table 1), such as what would constitute good practice or whether the suffering was ‘avoidable’. In some cases, you might provide a qualified opinion, for example, you may be asked if you can see any reason why the suffering would have been necessary, without saying that it was unnecessary. So your opinion can be helpful to the court without you feeling that you need to answer the legal question for them. Ultimately, that is for the court to decide.

Table 1:

Aspects of necessity and how veterinary opinion may assist the court

Forming an opinion

This paper cannot tell you what opinion to form – and nor should anyone else. Your opinion must be your own, formed by assessing the factual evidence and interpreting it. Giving an opinion can, in some ways, be considered along the same lines as consent (as previously discussed in the first paper of the series [Yeates 2017]). It should be informed, within your competence, and free from undue external influence.


An opinion about the case should be based on the facts of the case. For example, based on principles of animal welfare science, determining suffering involves a consideration of: the animal's circumstances (eg, its environment, whether it was beaten); physical and pathological states (eg, its pathology and body condition); and/or the animal's responses (eg, physiological measures or behaviour). Any or all of these can help to determine whether any suffering occurred and its degree and duration. For example, if an animal has been observed to be severely emaciated, then a veterinary surgeon may consider that their opinion on whether it suffered is not dependent on the exact aetiology of the emaciation (although finding out such information may be helpful in answering other questions).

Many relevant facts are likely to be ones that the veterinary surgeon did not personally observe. They may include facts witnessed by other professionals (eg, the case vet or laboratory technicians) or investigating officers (eg, a policeman or APHA inspector). A veterinary surgeon is not the investigating officer and does not have a duty to interview witnesses, but may need to see interview records. An expert is entitled to ascertain facts from others, in particular other witnesses' statements, although you should identify the sources of these facts and note in your report the fact that ‘person A’ informed you of ‘fact B’.

You should consider all relevant facts before forming and providing an opinion to the court, including those that do not support or may weaken your concluded opinion. You should therefore want to see, and be able to consider, all the evidence available. In some cases, depending on the matter in question, case vets may not need a lot of additional information beyond their own personal observations. In other cases, you may need access to statements and reports from the other parties to the proceedings. You should take reasonable steps to check that all of the information is correct within reason (eg, you should not need to re-interview all the witnesses personally). Where possible, it is better to record one's own observations before seeing others' testimony (eg, if both you and an inspector attend a house, then you can write your notes before reading their witness statement). However, in some cases you may need to obtain information from the inspector earlier (eg, information about the animal's environment as part of clinical history taking) before you give an opinion on the suitability of that environment.

Even with all the relevant available information, any opinion is conditional in that it is only based on the information that the veterinary surgeon has (and a vet may not be aware that they lack information that could be relevant to the case but was unavailable). For example, additional information may come up during examination of witnesses during court proceedings. All opinion should therefore be provisional, predicated on the information available to you. Indeed, in some cases, it may be useful to highlight some ‘known unknowns’ (eg, if there is information that the veterinary surgeon would consider to be useful but knows is unavailable). If, on further investigation, additional information should come to light, then you should be open to changing your opinion.

Area of expertise

You should keep within your genuine area of expertise. If a particular question falls outside your expertise, you should make it clear that you consider the matter to be outside of your expertise. Some veterinary surgeons find it helpful to consider their expertise in similar ways to their ‘competence’ – you do not have to be a world expert on a certain species or condition, but should be able to provide a reliable and valid opinion. While veterinary surgeons should not feel pressured into providing an opinion, you should be confident and willing to give opinions within your area of competence, even if you are not a specialist. All vets are generally considered experts for the court, because we are experts compared to the people that are magistrates or judges. It is part of being a professional.

You should be able to justify the decision to provide your opinion. An expert opinion needs to be reliable and should be formed using appropriate methods, such as valid laboratory tests, and sufficient evidence to provide a basis for the opinion (Table 2). Opinions should be based on animal welfare and veterinary science. Any sources of generic information, such as scientific papers, should be of the highest quality (eg, peer-reviewed) and cover the most up-to-date available and relevant research. However, assisting the court means that you should not try to confuse the court. You should help them to find out what is reasonably likely to have happened. This means that, while you should be thorough in considering differentials, you should not exaggerate the likelihood or unnecessarily obscure and confusing possibilities – you should be careful to not ‘muddy the water’.

Table 2:

Factors a court may take into account in determining the reliability of expert opinion (adapted from criminal practice directions amendment no 2 [Royal Courts of Justice 2014])

Free from influence

The duty of an expert witness is to provide independent assistance to the court by way of objective, unbiased opinion in relation to matters within their expertise (Ministry of Justice 2015). Your opinion must be free of any influence, including any financial arrangements. Your duty to the court overrides any duty to your client or to whoever is paying and instructing you (see R v Harris and others [1980] [Moles 2005]).

You can be the witness, of any type, for your own practice clients – so long as you feel comfortable and impartial. You should not let your opinion be affected by your views on the character of the person or the morality of the purported action. Expert witnesses have immunity from civil litigation in respect of evidence they give in court and statements that they make for the purpose of giving evidence. Such evidence should also not constitute a breach of confidentiality or data protection.

You can also be a witness when employed by an authority, and it is not necessary for you to take a mix of cases for the defence and prosecution (and you may not be asked to). What is important is that you are not influenced by other factors. One way to test your independence is to consider when you begin to review evidence whether you do so with a genuinely open mind. If you are already a priori ‘looking for’ evidence to support one view over an another, then you should decline from giving an opinion. If a solicitor offers to make payment contingent upon the nature of the evidence you give, then they should be reported to their regulatory body.

Combining multiple roles

In general, the primary ‘case vet’ will always be required to provide testimony concerning the facts within their personal knowledge. Others cannot provide the same factual information since it is not within their own knowledge (they could only obtain it from the case vet).

In most cases, the case vet will also be asked to provide an opinion. This has the advantage of meaning the professional who actually examined the animal gives an opinion based on their first-hand observations and findings. As an expert, you may have then been given access to other evidence on which to base your opinion (eg, witness statements, other veterinary surgeons' reports), and this should not alter your original report of the facts from the earlier casework.

In other cases, the clinical and/or forensic work will have been done by one veterinary surgeon – a primary case vet – and another veterinary surgeon – a secondary expert – may then provide an opinion based on the case vet's reports. Examples where this may be necessary include:

  • When there are multiple vets involved in the casework and one provides an overarching opinion,

  • When a case vet does not want to present an opinion in court for personal reasons,

  • When the defence instructs an additional expert to give another view, or

  • When some questions are outside of the competence of the initial case vet.

In some cases, when acting as a secondary expert, you may feel that you need to clinically examine the animal yourself, thereby also making you a witness of fact. However, you need to consider what can be gained from this and whether the information could be better gained in another way. For instance, an up-to-date body condition score or repeat blood sample can be done by another vet who then provides a short factual statement. In many cases, by the time a secondary expert is involved in the case there is little point seeing the animal/ as their current condition bears little resemblance to the condition at seizure.

It is not for the second vet to speak or write disparagingly about another veterinary surgeon and colleagues should be treated fairly and with respect (RCVS 2016). Their role is also not to critique the clinical care or forensic skills of the case vet per se. However, secondary experts should note where there are matters of which the court should be aware when assessing the reliability of your opinion. For example, if a colleague's examination has missed out something relevant, then this should be drawn to the court's attention in a professional way. Again, this should avoid unnecessarily muddying the waters.


Being an expert witness should not be overly daunting; it should be within veterinary professionals' competence and is an important part of helping animals and the judicial system. All practitioners should constantly bear in mind their professional and legal duties, recognising that these are largely focused on being thorough and fair.


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