Top 10 Tips on Expert Evidence for Clients

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This article was written by Fiona Hotston Moore, a highly regarded Expert Witness and Forensic Accounting Partner at FRP Advisory.

Lawyers and barristers understand legal cases often fail or succeed based on the quality of expert evidence presented in court. However, the role of expert witness is often not understood by the layperson and client.

Most clients are aware of the role of the witness of fact in a court case. A witness of fact gives evidence on the facts as known to them and must avoid giving an opinion.

An expert witness is engaged to give their opinion on an issue that is outside the court’s expertise. Experts are instructed to assist the court in understanding a technical matter which might be financial, medical, scientific or professional.

The expert witness in larger cases is often selected by the lawyer with input from the barrister. In smaller cases, or where the client acts as “litigant in person” and in situations where the expert is instructed as a Single Joint Expert, the client may be directly involved in selecting their expert.

As an expert, I have experience of acting in a wide spectrum of cases and seeing the work of other experts. Based on my experience, I share my Top 10 Tips on obtaining expert evidence to deliver a successful outcome.

1. What are the key considerations in selecting an expert witness?

  • an expert should be experienced in the role and responsibilities of an expert witness. I have on several occasions been instructed to replace an individual who has been engaged to give an expert report but had no idea how to prepare a report for court. There are professional bodies that provide formal accreditation of expert witnesses
  • the expert must be clearly experienced and appropriately qualified in the area in which they will give an opinion and must be credible to the court and the parties as an expert. Wherever possible I would recommend meeting the proposed expert in person and objectively assess their credibility. Do you respect their view?
  • the expert should not be appointed based on the cost estimate – it will be a false economy. The cost of an expert must be proportionate, but I would advise against selecting an expert based on cost.

2. Engage your expert witness early in the dispute

In my experience, the expert witness can identify the key issues, give an independent opinion on the strength of the arguments and quantum and facilitate an early settlement. I have been involved in several cases where the provision of my report has facilitated an early settlement of the matter avoiding an escalation of legal costs and the stress involved in lengthy litigation. I have also assisted in mediation to help the parties and the mediator understand the issues and reach settlement.

3. How do I ensure I am going to get the expert report I want?

The expert witness owes an overriding duty to the court and must provide an objective and fair opinion. Furthermore, they are not going to help you if they act as a “hired gun” and provide an unreliable biased opinion which is shown to be so in Court. However, it is good practice to obtain an initial advisory opinion from the proposed expert before formally appointing them as your expert.

Also remember, if your expert witness cannot give the strength of opinion you seek, it may be that you should be considering an early settlement of your claim.

4. Effective letter of instruction

In my experience, the expert witness can be most effective if the instructing lawyer invests the time at the start in providing a well-constructed letter of instruction. A well-formed letter of instruction provides:

  • adequate background to the case and the key issues
  • a core bundle of the key documents
  • an indication of what further evidence is available
  • clear direction on the relevant legal test(s)
  • specific instructions on which an opinion is sought
  • clarity on the timetable.

In larger cases, it is helpful if the barrister is consulted in drafting the letter of instruction.

5. How do I control the costs of the expert witness?

As I have noted, I do not recommend selecting an expert based on the cheapest quote. The expert’s fee is a relatively small element of the professional costs of litigation. The cost of an expert must however be proportionate.

Once the expert has had the opportunity to familiarise themselves with the case, possibly after providing an initial advisory view, the expert should be asked to provide a fee estimate for their expert report and all the potential further stages up to and including cross-examination.

The expert witness must be independent and therefore cannot act on a success basis.

6. When should I appoint a Single Joint Expert?

The Single Joint Expert (SJE) is instructed jointly by all parties to a dispute and gives their independent unbiased opinion to all parties. An SJE is usually appointed to contain costs and to assist efficiency. Typically, an SJE is instructed in divorce cases and sometimes in shareholder and other civil disputes.

In appointing an SJE, often three names are put forward and one is appointed. This can be the cheapest and again I stress this can be a false economy. Not all experts are the same. In selecting an SJE you should still consider their experience, their credentials and their availability.

7. How can I get help in assessing an expert report?

Any party to a dispute can get assistance from a Party Adviser or “shadow expert”. This is typically another expert who sits in the background and helps one party (and their legal team) in assessing the expert report of the other party’s expert and suggesting appropriate questions. A shadow expert is often a modest cost and can be extremely helpful in identifying the strengths and weaknesses of the other expert’s report. It may also be possible to obtain court permission to appoint a Party Expert in matters where there is already a Single Joint Expert.

8. Should I consider “hot tubbing”?

Hot tubbing is the new practice of hearing concurrent evidence by having all the experts in the witness box together. Some judges consider that hot tubbing is more efficient and effective than cross-examining each expert individually. An expert will summarise his report or the opinion on one aspect of the case and will then be questioned by the judge, the other expert(s) and the parties. The process tends to be more challenging for the experts and the interactions can be revealing.

9. Preparing your expert witness for cross-examination

The expert witness must not rehearse their evidence with their instructing barrister. However, they do need to be fully prepared for cross-examination and typically will have explored the strengths and weaknesses of their evidence with a colleague. Formal expert witness training by a professional training provider can be really helpful on larger cases. Such training is not specific to the case but focuses on how to deal with cross-examination and court protocol.

10. And finally, my top tip in avoiding costly litigation

My final tip is to try and avoid litigation by obtaining legal advice at the onset of commercial and family arrangements to ensure that appropriate legal contracts are put in place. Such contracts will typically include terms outlining how disputes are to be resolved and parties can exit the relationship. All too often I am engaged in partnership disputes where there is no partnership agreement or shareholder disputes where there is no shareholders agreement. These documents play an important role in managing a business relationship and avoiding costly disputes.

Free On-Demand Webinar: All you need to know about Expert Evidence, but were afraid to ask

Ashtons Legal Disputes Partner, Michael Frape posed the questions that many clients are understandably afraid to ask to Fiona to provide you with an opportunity to get up to speed with the basics of expert evidence.

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For further information about expert evidence and to instruct Fiona on your case, please visit the FRP Advisory website or email Fiona on

Ashtons experienced Dispute Resolution team are able to assist you with business or personal disputes. You can contact them through this website or by calling 0330 404 0749.


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