What is an expert witness?
A decision maker in a Tribunal or Judge in a Court of Law has expert knowledge of the law but does not have expert knowledge of every aspect of every trade profession, like for example, quantity surveying. So a Judge requires independent expert evidence about specific issues, and rightly so, because otherwise you would have a situation where a Judge is providing his own evidence, something that I am sure you would agree could not be seen as fair. However, that scenario can arise when an expert Arbitrator or Adjudicator presides over a dispute, but in that circumstance the Arbitrator or Adjudicator must be careful to seek the opinion of the parties on the evidence, thus preventing a subsequent claim for a breach of natural justice. It is also a fact that an Arbitrator or Adjudicator is usually chosen by the parties because of his/her expert knowledge.
The other type of witness before a Court is a witness of fact. Such witnesses cannot give their
opinion on the circumstances giving rise to the matter before the Court. If they do, that opinion would likely be disregarded by the Court as they would not be regarded as being independent; a critical factor in being recognised as an expert in the Court.
Whilst being cross-examined, the expert witness can and does give detailed explanations of why he/she holds that opinion, but a witness of fact is often just required to answer “yes” or “no”.
In Jones v Kaney, Lord Phillips observed at  that:
“A significant distinction between an expert witness and a witness of fact is that the former will have chosen to provide his services and will voluntarily have undertaken duties to his client for reward under contract whereas the latter will have no such motive for giving evidence… there is a marked difference between holding the expert witness immune from liability for breach of the duty that he has undertaken to the Claimant and granting immunity to a witness of fact from liability against a claim for defamation, or some other tortious claim, where the witness may not have volunteered to give evidence and where he owes no duty to the claimant.”
At (50) Lord Phillips expressed the position of the expert witness vis-à-vis the advocate in the
“Thus the expert witness has this in common with the advocate. Each undertakes a duty to provide services to the client. In each case those services include a paramount duty to the court and the public, which may require the advocate or the witness to act in a way which does not advance the client’s case. The advocate must disclose to the court authorities that are unfavourable to his client. The expert witness must give his evidence honestly, even if this involves concessions that are contrary to his client’s interests. The expert witness has far more in common with the advocate than he does with the witness of fact.”
CODE OF CONDUCT FOR EXPERT WITNESSES IN THE DISTRICT AND HIGH COURTS
District Court Rules 2014 paragraph 9.34 effectively refers to the High Court Rules:
High Court Rules – Schedule 4:
The Weathertight Homes Tribunal:
DUTY TO THE COURT (HIGH COURT RULES)
1. An expert witness has an overriding duty to assist the court impartially on relevant matters within the expert’s area of expertise.
2. An expert witness is not an advocate for the party who engages the witness.
EVIDENCE OF EXPERT WITNESS
3. In any evidence given by an expert witness, the expert witness must –
(a) acknowledge that the expert witness has read this code of conduct and agrees to comply with it;
(b) state the expert witness’ qualifications as an expert;
(c) state the issues the evidence of the expert witness addresses and that the evidence is within the expert’s area of expertise;
(d) state the facts and assumptions on which the opinions of the expert witness are based;
(e) state the reasons for the opinions given by the expert witness;
(f) specify any literature or other material used or relied on in support of the opinions expressed by the expert witness;
(g) describe any examinations, tests, or other investigations on which the expert witness
has relied and identify, and give details of the qualifications of, any person who carried
4. If an expert witness believes that his or her evidence or any part of it may be incomplete or inaccurate without some qualification, that qualification must be stated in his or her evidence.
5. If an expert witness believes that his or her opinion is not a concluded opinion because of insufficient research or data or for any other reason, this must be stated in his or her evidence.
DUTY TO CONFER
6. An expert witness must comply with any direction of the Court to –
(a) confer with another expert witness;
(b) try to reach agreement with the other expert witness on matters within the field of expertise of the expert witnesses;
(c) prepare and sign a joint witness statement stating the matters on which the expert witnesses agree and the matters on which they do not agree, including the reasons for their disagreement.
7. In conferring with another expert witness, the expert witness must exercise independent and professional judgment, and must not act on the instructions or directions of any person to withhold or avoid agreement.
The Weathertight Homes Tribunal has a very similar set of rules.
Typically an expert will be engaged to provide a report to a client or their legal representative surrounding a building. That report, if given for the purposes of litigation to a client’s legal advisor, will be legally privileged; that is, it can be claimed as privileged information by a lawyer and not disclosed to the other parties to a dispute. The report is initially given to provide expert advice to a legal practitioner who has to assess whether a breach of the law has occurred. When a report is not used it is normally a situation where the experts report is not helpful to the clients cause.
Where a report does not eventuate into an action then that report remains confidential to the client and will not be divulged to any other party without that client’s written consent.
If the matter progresses to Court, Arbitration or any other dispute resolution process then the expert would normally be required to provide a sworn Affidavit, that is a written statement of fact witnessed by a JP or solicitor or alternatively a Brief of Evidence, sometimes called a Witness Statement, which is written based on the report and/or other facts that have come to light.
A Brief of Evidence or Affidavit includes the expert’s qualifications to provide the evidence, that is the parties and the Judge have to be satisfied that the expert is an expert in matters pertinent to the evidence. Evidence should be easy to understand and the goal is for your neighbour’s 14 year old daughter to understand it.
Building surveying evidence revolves around building defects, reasons for / and consequent damage to a building. That evidence revolves predominantly around the Building Act 2004. Quantity surveying expert evidence generally revolves around the related quantum of loss, expense claims and delay analysis.
The expert must stick rigidly to his or her area of expertise, and as an expert you must not stray from it, as doing so puts the evidence at risk of being dismissed by a Judge, which does not help your client or your reputation and consequent future work.
Finally, the expert is not an advocate for a client but provides impartial and unbiased evidence for a decision maker to help them make a just decision.