Duties of an Expert Witness

Experts’ duties

An expert may be called upon to do any or all of the following:

·         investigate the facts;

·         form opinions,

·         advise their client and their client’s lawyers,

·         prepare evidence,

·         propose remedial works.

In all of this, within their own role and competence, they owe a duty of care, both in contract and tort, to their client.  Unless they are legally qualified their responsibility is restricted to technical matters, excluding advice on legal procedures or on the likelihood of success should litigation or arbitration be pursued.  The extent of their responsibilities is defined by the skills they hold themselves out as having, and the agreement they enter into with their client.  As with any appointment for professional services, it is important that they agree, at the outset, the extent of their responsibilities.

They have a duty to the court to be truthful, which overrides their duty to their client and makes it most unwise for them to deliberately omit or falsify facts to disguise the truth.  Accordingly, to ensure that they feel able to speak freely in court, experts’ liability to their clients is limited.[1]  They should not address matters which are outside their brief, and on which they are not questioned.

Court may appoint experts,[2] in which case their role may have some similarity to that of an arbitrator in respect of the issues within their expertise.  Their role is, nonetheless, advisory.

Expert witnesses’ duty to the court overrides any obligation they have to the person who instructs or pays them.  To discharge this duty, experts must be completely open in revealing to the court all relevant matters whether or not they go against their client.  Accordingly, to ensure that they feel able to speak freely in court, experts’ liability to their client is limited. [3]



[1]  Court Procedure Rules, R 35.3(2).

[2]  Order 40, rule 1.

[3] Court Procedure Rules, R 35.3(2)