An expert evidence presenting information in a Court room seen from behind holding paperwork

Expert evidence plays a crucial role in legal proceedings to help the courts understand complex issues that go beyond the general knowledge of most lawyers and judges. In some cases, it is therefore incredibly useful to have an impartial and objective professional with the relevant expertise to comment on the key issues of a case. Experts can give evidence on a range of matters, from technical or scientific matters to specialist practice or procedures. Whatever the specialism, expert evidence can help clarify the facts and guide the judge to a fair decision.

When can the court allow expert evidence?

There are specific rules regarding when and how expert evidence can be used in legal proceedings and parties must actively make an application to the court to be able to call an expert witness.

Expert evidence may not be relevant for every case – it will only be allowed by the court where it is ‘reasonably required’ to resolve the proceedings (CPR 35.1). There is therefore no hard and fast rule about when it will be admissible, and it will likely depend on the context of the claim. However, when considering whether to admit the evidence of an expert, the court will have regard to the following principles:

  • Whether the expert is qualified in a formally recognised discipline
  • Whether the expert evidence is necessary
  • Whether the expert evidence proposed will genuinely help the court
  • The kind of evidence (i.e. fact and/or opinion) the expert will give

Further guidance comes from the case of Kennedy v Cordia (Services) LLP [2016] UKSC 6; where the Supreme Court set out the key issues the court need to address when using expert evidence: 

  1. Whether the evidence will assist the court;
  2. Whether the witness has the necessary knowledge and experience;
  3. Whether the witness is impartial in his or her presentation and assessment of the evidence; and
  4. Whether there is a reliable body of knowledge or experience to underpin the expert’s evidence.

Our legal advisors are able to assess whether the proposed expert has the necessary qualifications and experience relevant to the dispute and can assist with instructing a suitable expert. We can also ensure that the experts are aware of their duties and obligations which is imperative in ensuring that the expert is impartial and reliable, as required by Kennedy.

Examples of circumstances where expert evidence may be required:

  • To quantify damages a business suffered because of wrongful actions by a director
  • To undertake a forensic review of bank statements or company accounts
  • To provide an objective valuation of a business which may include a detailed report of its assets and liabilities
  • To determine a diagnosis of injury caused by an accident and the extent of the loss sustained
  • To provide an objective opinion on property valuations or boundary disputes

The range of potential expert witness evidence is extremely broad and reflects the varied subject matter of legal disputes.

When might evidence be inadmissible?

There are circumstances in which a court may find expert evidence inadmissible or where they withdraw permission. Some of the key reasons for this include:

  1. Lack of expertise: If the expert does not have the necessary experience of qualifications relevant to the case then their evidence is unlikely to be credible.
  2. Irrelevance: If the evidence does not directly address a key issue of the case, the court may not deem it just or proportionate to have an expert.
  3. Unreliable methods: If the methods or principles the expert uses are not scientifically valid or considered unreliable in their field, their testimony could be excluded. Courts will examine whether the expert’s methods are based on widely accepted practices.
  4. Speculation or opinion: Evidence based on anything other than facts or reasonable inferences is unlikely to be admissible.
  5. Partiality: If the expert is influenced by one of the parties or is not sufficiently independent then the court may rule that the evidence is inadmissible.

It is also important to be aware of the factors set out in the above case of Kennedy, as you may need to consider their relevance in relation to the other party’s expert evidence, if it is necessary to make an application to have their expert evidence ruled inadmissible.

Conclusion

Expert evidence can be a powerful tool in litigation, helping the court navigate complex issues and ensuring that decisions are made based on a deep understanding of the issues at stake. However, expert evidence must meet certain standards in order to be admissible. It must be relevant, reliable, impartial and based on expertise that is recognised in the field. If these requirements are not met, the court may rule the expert evidence inadmissible.

This article was co-written by Isabella Kershaw and Stephen Wray, solicitor and partner in our Commercial Dispute Resolution team.