This guide is one of a series of guides to the main types of dispute resolution processes. It seeks to answer some of the questions most frequently asked by clients involved in adjudications, and to provide an overview of the process.

About this Guide

This guide provides an introduction to the use of witness and expert evidence in litigation.

What is Evidence?

Once a claim has been pleaded, in order for it to be successful the claimant must prove its case on a balance of probabilities. To do this, the claimant will need to adduce sufficient evidence to support its claim.

Evidence can be found in documents, people’s testimonies as to the facts of the matter (witnesses of fact), and in the opinion of an expert in the relevant field (expert witnesses).

Evidence found in documents is dealt with in our guide to disclosure, and therefore this guide will focus on witness evidence and expert evidence.

Witnesses of Fact

Where a dispute has arisen, those involved will be able to give factual evidence as to what happened and when. Facts which need to be proved must be proved at trial by oral evidence.

However, a judge may determine a case on the basis of evidence already received and further written evidence if requested (witness statements, schedules). [Guidance note 32.2.1, White Book 2020]

The Court usually directs that a party who wishes to rely on the evidence of a witness must serve on the other parties in advance of trial a statement containing the witness evidence in written form, signed with a statement of truth.

Once a witness statement has been served, it will stand as the witness’s “evidence in chief” at the trial. This means that the witness does not need to repeat its contents but must attend trial to swear or affirm to its truth. The witness will then be cross-examined by the other side on the contents of the witness statement.

Not everything the witness has to say will necessarily be relevant. It is good practice to interview all potential witnesses as soon as possible after the dispute has arisen so that the material facts and events are fresh in their minds.

However, by the time witness statements are finalised and signed, the claim will have been pleaded and key documents will have been exchanged between the parties, meaning that the issues to be tried will have been identified. Witnesses only need to give evidence on those issues in dispute, and therefore the content of the finalised witness statements should be focussed only on those issues.

A witness of fact is not able to give opinion evidence. They are there to assist the Court by giving evidence on material facts and events. Of course, opposing parties will always adduce conflicting evidence and it will be for the Court to decide, on a balance of probabilities, whose version is to be believed.

There is no property in a witness, meaning that either party can seek to adduce evidence from any person who has information helpful to their case. Not every person they approach may be willing to give evidence, however. In that case, a party can draft and serve a “witness summary”, identifying the witness setting out the evidence that party believes the witness would give at trial as if they had given a witness statement. Attendance of a reluctant or unreliable witness at trial can be compelled by the issue of a witness summons.

Expert Witnesses

In cases where the Court deems it appropriate (e.g. cases which turn on a technical matter), the Court will permit parties to serve expert evidence. The Court will consider if engaging experts would be excessive, cause delay or increase complexity.

Where the parties apply for permission to engage an expert they must provide an estimate of the costs of the proposed expert evidence.

Expert evidence takes the form of a witness statement from a sufficiently qualified and experienced person, who gives an opinion on a relevant matter. This evidence is intended to assist the Court when having to consider a technical matter which the Court cannot decide upon without expert input.

The Court could order one expert to give an opinion on a particular matter, upon joint instructions from both parties (known as a “single joint expert”). Alternatively, in more complex cases, the Court could order that each party be permitted to obtain their own expert opinion. Where each party does instruct their own expert, it is usual for the experts, once they have finalised their reports, to try and agree between themselves which issues they agree upon and which they do not. This is intended to assist the Court in identifying those issues which need further examination at trial.

Although experts are instructed and paid for by the parties, their overriding duty is to the Court. Therefore, the opinion they come to must be objective. The experts must remain impartial.

Like witnesses of fact, expert witnesses can be cross examined by the parties, and it is therefore usual to instruct experts who have Court experience and whose opinions are able to stand up to scrutiny.

About us

Our experienced lawyers regularly represent clients in evidence cases.

If you have any questions about this guide or any other matters please do not hesitate to contact one of the following members of our Dispute Resolution Team at [email protected] or contact our Head of Department:

Robert Oakley

[email protected]

DD: +44 (0)20 7551 7792 | Tel: +44 (0)20 7551 7777 | Mob: +44 (0)7891 143 718

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