The requirement for expert evidence is almost taken for granted in construction and engineering disputes. It is assumed that the technical nature of the issues will be sufficiently complex that the court will need specialist input to understand them, and that such input will be required in relation to a number of different disciplines/technical issues.

However, experience shows that the understanding of what “expert evidence” actually is may be unclear. Often, parties assume that merely retaining an “independent” third party in relation to technical issues is sufficient to enable them to present, and rely upon, that evidence at court. That it not so. In addition, the treatment of experts may vary from jurisdiction to jurisdiction, and in accordance with the applicable arbitration rules/protocols that are in place.

Using examples from a variety of common law jurisdictions and arbitration rules, this article revisits the basic premises of expert evidence, and provides an overview of the applicable requirements.

1. There are a number of different types of ‘expert’

Different types of experts may be retained in relation to construction and engineering disputes. The types of expert are:

  • Expert witness – this is a person who has been instructed by a party to prepare and give expert evidence for the purpose of court or arbitration proceedings.1 Unlike a witness of fact, an expert witness is permitted to give opinion evidence on matters within his/her technical expertise; and
  • Expert adviser/consultant – sometimes known as an ‘independent expert’, this is a person who advises a party on a specialist or technical matter within his/her expertise at any stage of the problem, dispute or claim.

Parties generally appoint their experts at an early stage, and often before matters have proceeded to formal court or arbitration proceedings. An early appointment of an expert should assist a party to identify the ‘real’ technical issues in dispute, and understand the technical merits of the case. However, an expert’s remit should be framed by its instructing party as early as possible. Difficulties often arise because an expert is initially appointed to investigate and advance a parties’ contentions, but subsequently has to provide independent expert evidence to the court.

2. It is important to choose an expert witness wisely

In some disputes, finding and retaining the ‘right’ expert witness quickly will be the most important step a party takes in the case. Making the ‘wrong’ appointment may prove to be disastrous for a party’s case. It is vital to ensure that an expert witness has the requisite technical expertise. It is also important to consider whether a potential expert witness:

  • Is familiar with the required duties and responsibilities (which will vary from jurisdiction to jurisdiction and/or will depend on the applicable arbitration rules/protocol in place). It is essential that an expert witness fully appreciates the extent of their obligations, and the work/preparation required to fulfil them.
  • Will undertake the work alone or be assisted by a team. Whilst it is common for expert witnesses to be assisted by a team (particularly in large and/or complex disputes), a party must ensure that the expert witness will be sufficiently involved throughout the matter, and not merely act as ‘front’ for someone else’s work at trial.
  • Has the capacity to meet the relevant aspects of the procedural timetable, prepare and submit his/her report, and attend the trial. You should assume that any court or tribunal will take a very dim view on any failure to comply with the procedural timetable. The unavailability of an expert witness is unlikely to be a sufficient ground for varying a trial window or a fixed trial date.
  • Has previously given evidence in litigation proceedings. The process of giving evidence by examination and cross-examination can be adversarial and stressful. It is important to ensure that an expert witness has the appropriate personal skills and capacity to deal with this process.

3. An expert witness has an overriding duty to the court

This principle expressly underpins the appointment of expert witnesses in a number of jurisdictions. For example:

  • Part 35.3 of the United Kingdom Civil Procedure Rules (“UK CPR”) obliges all expert witnesses to help the court on matters within their expertise, and makes it clear that this obligation overrides any obligation to its instructing party; and
  • Practice Note CM7 in the Federal Court of Australia expressly states that an expert witness is not an “advocate” and has a “paramount” duty to the court and not its instructing party.

These jurisdictions also require expert witnesses to include express statements within their reports which confirm that: (i) they understand their duty to the court (and/or the duties as set out within the applicable Code of Conduct/Practice Note); and (ii) they have complied with that duty.

Similar levels of scrutiny exist within International Arbitrations, with the IBA Rules of Evidence (the “IBA Rules”) requiring expert witness reports to include “a statement regarding his or her present and past relationship (if any) with any of the Parties, their legal advisors and the Arbitral Tribunal” 2 and “a statement of his or her independence from the Parties, their legal advisors and the Arbitral Tribunal”.3

In the United States of America, however, there is no code of conduct for expert witnesses and no definition of an expert witness’ duty to the court. As a result, expert witness reports are also not required to include statements which confirm that they have complied with their duties, or which confirm that they are independent.

In those jurisdictions where an expert witness is required to comply with a duties to the court and/or which are set out in Codes of Conduct/Practice Notes, the courts may impose sanctions in the event of an expert witness’ failure to comply. In extreme cases, and if the court considers that it has been misled, the general powers for contempt of court can be invoked. In such a situations a wrongdoer may be fined or imprisoned.

Accordingly, and as a minimum matter of good practice, parties to disputes should be clear about the extent of their requirements (and likely future requirements) prior to engaging an expert to assist it with its case. If a party’s expectation is that an expert advisor/consultant will subsequently act as an expert witness, it must ensure that some degree of independence is maintained throughout the experts’ period of initial involvement. If not, there is a risk that he/she may be subsequently perceived as a ‘hired gun’, and lacking in the requisite impartiality/independence to fulfil the role of expert witness.

4. Courts restrict the use of expert witness evidence

Courts generally place checks and balances on the type, and extent, of expert evidence which may be used in litigation proceedings.

In the UK, Part 35 of the UK CPR limits the use of expert evidence “to that which is reasonably required to resolve the pleadings4 and to reduce “the … inappropriate use of experts to bolster cases5. A similar approach exists in the United States where, by virtue of Rule 702 of the Federal Rules of Evidence, the provision of opinion evidence by Expert Witnesses is limited to those who are “qualified as an expert by knowledge, skill, experience, training, or education”. The approach in International Arbitrations is broadly similar to that in the United States, as the IBA Rules of Evidence envisage that a parties shall only rely on the evidence of expert witnesses on “specific issues”.6

What this means at a practical level will vary from case to case, and jurisdiction to jurisdiction. The UK case of British Airways Plc v Spencer and 11 others (present trustees of the British Airways Pension Scheme)7 recently advocated the adoption of a uniform approach and said that, when determining whether expert evidence should be admitted, a court should look at the pleaded issues and asking the following “important questions”:

  • Is expert evidence necessary to resolve each issue? If evidence is necessary, and not just helpful, it must be admitted.
  • If expert evidence is not necessary, would it assist the court in resolving the issue? If expert evidence would assist, but is not necessary, the court should be able to determine the issue without it.
  • If expert evidence is not necessary, is it reasonably required to resolve the proceedings (taking account of factors such as the value of the claim, the likely impact of the judgment, and who will bear the costs of the expert evidence)? If expert evidence is reasonably required, it may be allowed by the court.

This guidance should be considered as a worthy reminder that, in the United Kingdom, parties are expected to carefully consider whether expert evidence is to the crux of the matter, and therefore necessary to resolve the issues in dispute.

5. There are various ‘general’ requirements for the reports of expert witnesses

Whilst no jurisdiction is likely to go so far as to prescribe the format that an expert witness report must take, many contain a number of general reporting requirements of which all expert witnesses should be aware.

It is a common (and understandable) requirement for an expert witness to provide details of his/her qualifications and/or a copy of his/her current CV. As set out above, a statement which confirms that the expert witness understands his/her duties, and has complied therewith, is also commonly required. Some jurisdictions require further, and more specific information. For example, in:

  • the United Kingdom, expert witnesses must provide details (including qualifications) of any persons who have carried out work (examinations, measurements, or tests) on their behalf; and
  • the United States, expert witnesses must provide details of the recent cases in which they have testified and the compensation that they are being paid.

Of greatest significance, and one which is adopted universally, is a requirement that an expert witness explicitly states the issues that he/she will be addressing and/or the substance of all material instructions that he/she has been given. Courts are very live to the fact that apparent differences in experts’ opinions may be derived from differences in the instructions given, and may not actually evidence genuine issues in dispute.

Expert witnesses must also “show their working out”. In addition to stating the opinions/conclusions that they have reached, expert witnesses must also outline the basis for those opinions/conclusions, and the information/analysis upon which they rely.

6. Courts scrutinise the costs associated with the use an expert witness

The costs associated with litigation proceedings are a concern to all parties involved, and courts are increasingly prepared (and obliged) to scrutinise the costs associated with the provision of expert witness evidence. After expert witness independence, the incurrence of excessive costs is the second greatest concern associated with expert evidence.

Various approaches have been adopted to address the issue of excessive costs head-on. The United Kingdom has perhaps taken the most radical and, since April 2013, a party applying for permission to use expert witness evidence must:

  • provide an estimate of the costs of the expert witness evidence; and
  • identify the field and the issues that the expert witness evidence will address.

The requirement to provide a costs estimate obliges parties to ensure that their expert witness’ costs budgets are based on realistic estimates and assumptions, and keep costs under review. The UK courts have shown that parties will be held to the cost budgets that they provide, and expert witness evidence will be restricted to the field and issues that they are permitted to address. In Parish and another v The Danwood Group8 the winning party made a retrospective application to increase its cost estimate for expert evidence. The original budget, which was set before the expert witness had been identified, included a figure of £20,000 for expert witness evidence. However, the expert witness subsequently incurred a fee of £70,000. The judge refused to increase the costs budget, and found that the expert witness’ instructions went beyond the field and issues that he was permitted to address.

7. Meetings, Discussions and Joint Statements

Expert meetings, discussions and joint statements are all used as a means to narrow the issues that will go to trial, and ultimately reduce the time and costs of the litigation proceedings.

Courts in the United Kingdom, Canada, and Australia all have the discretion to order that opposing expert witnesses hold discussions and/or meetings in advance of the trial. Similarly, the IBA Rules allow the Arbitral Tribunal to order that the opposing Party-Appointed Experts “meet and confer” on issues and “attempt to reach agreement on the issues within the scope of their Expert Reports”.9 The practice is not, however, common in the United States.

The purpose of these discussions is for the expert witnesses to agree and narrow issues and, in particular, to identify the extent of the agreement between them, and the points of any disagreement. The product of these discussions/meetings is a signed joint statement dealing with each of the above points.

Whilst there is a clear benefit to meetings and discussions taking place, and the production of joint statements, parties should be live to the potential consequences of experts reaching and communicating any agreements. In the United Kingdom, courts have shown that they take a dim view if an expert witness subsequently tries to renege on an agreement recorded within a joint statement. In Denton Hall Legal Services and others v Fifield10 an expert witness retracted a signed joint statement. The court considered that the retraction had:

"plainly damaged his credibility as an expert witness... At best, [he] had been careless: at worst, he ran the risk of being accused of tailoring his evidence to fit in with [the defendant's] case".

8. Single Joint Experts

These are experts who are instructed to a prepare a report for the court on behalf of two or more parties to a dispute or claim.

Their use was first suggested in the United Kingdom, in Lord Woolf’s 1996 Access to Justice Report, in which it was suggested that they be used where the case is concerned with a “substantially established area of knowledge” and/or where it was unnecessary for a court to “sample a range of opinions.”

Whilst the UK CPR gives the UK courts discretion to order that a single joint expert be instructed, other jurisdictions have gone one step further. For example, in Australia, the Civil Procedure Rules of the Supreme Court of Queensland provide that:

“if practicable and without compromising the interests of justice, expert evidence is given on an issue in a proceeding by a single expert agreed to by the parties or appointed by the court”11

In other jurisdictions however, such as the United States, there is no provision for the use of single joint experts, and the preference for each party appointing their own expert (and for those experts to report separately and be cross-examined) has been maintained. The same is broadly true in International Arbitrations. Whilst the IBA Rules provide for the appointment of Tribunal-Appointed Experts, the use of Party-Appointed Experts continues to dominate.

In instances where a single joint expert is appointed, the parties should attempt to devise a protocol covering all aspects of the appointment including, as a minimum: the terms of reference; the procedure for the expert to seek further information, documents, and instructions; and payment of fees.

In addition, and in particularly complicated cases, parties may wish to still engage and consult their own expert advisers on the work of the appointed single joint expert. This practice is typical in Australia, and is often cited by critics as evidence that the imposed use of single joint experts does little to save costs or improve settlement prospects.

9. The court can order that expert witnesses give oral evidence concurrently

The legal slang for this process is “hot-tubbing”. It involves opposing expert witnesses giving evidence at the same time and in each other’s presence. Generally, questions are put to each expert by the judge, who effectively acts as the ‘chair’ of the debate between the experts. Expert witnesses are enabled to ask questions of each other, and to respond to each other’s answers.

In Australia the practice dates back to the 1970s, when it was originally used in commercial tribunals. Since then, it has found favour in both the Federal Court of Australia, and in a number on state courts. In the United Kingdom and Canada “hot-tubbing” has only been used more recently, and in neither jurisdiction has the process been widely adopted. In November 2014, Lord Neuberger opined, that with respect to the United Kingdom:

“[It] would be wrong to form any sort of clear view that we should either avoid, or go over to, hot-tubbing generally, until we have gathered a statistically meaningful number of cases with hot-tubbing experts, and a statistically meaningful number of cases where the normal adversarial approach is adopted. With such evidence it should be possible to assess the relative merits of the adversarial and hot-tubbing systems.”

With respect to International Arbitrations, the IBA Rules of Evidence enable the Arbitral Tribunal to order, or a Party to request, that expert witnesses “be questioned at the same time and in confrontation with each other”.12 A recent survey13 of arbitration participants confirmed that 60% of the respondents had experienced “expert witness conferencing” in the arbitrations that they had been involved in.

In contrast, the United States has largely resisted hot-tubbing in favour of maintaining the status quo of the examination and cross-examination of expert witnesses.

The perceived advantages of the procedure include a greater focus on the issues in dispute before trial, a better use of time at trial, and potential costs savings. It is, however, a significant departure from the normal practice of examination and cross-examination. Counsel effectively lose control of process and, by time it gets the opportunity to ask questions of each expert witness, the damage to a party’s case may already have been done.

10. Experts may be liable to their clients for their breaches of duty

Originally, expert witnesses enjoyed immunity from suit for any breach of duty in the preparation for, or involvement in, legal proceedings.

In the United States, there has been some erosion to this immunity since the 1990s, and malpractice claims and claims for negligent performance have been permitted in both the federal and state courts. Examples of the United States’ approach towards the erosion of expert witness immunity are found in the cases of:

  • Murphy v A.A. Mathews14 - in which the Missouri Supreme Court found that no expert witness immunity exists for negligence by a professional providing an agreed service;
  • Boyes-Bogie v Horvitz15 – in which the Massachusetts Superior Court held that the doctrine of witness immunity did not bar a claim where an expert did not comply with the applicable professional standards.

In the UK, the Supreme Court removed the immunity for expert witnesses in 2011, in the case of Jones v Kaney16. In doing so, the Supreme Court commented that it did not consider that there was any conflict between the duty of care that an expert witness owes to its client and the duty it owes to the court, and that there was no clear reason why an expert required immunity from liability for negligence. However, and perhaps as a means of reassurance, various Justices within the Supreme Court opined/noted that:

  • if an expert witness gives an independent and unbiased opinion, which is within the range of reasonable expert opinions, he/she will have discharged his/her duties to the court and his/her client.
  • the courts should be alert to protect expert witnesses against "specious claims" by disappointed litigants.
  • most expert witnesses are professional people who are insured or can limit their liability by contract.
  • the removal of immunity may have other positive impacts for parties and litigation. For example, expert witnesses may be less likely to pitch their initial views of the merits of a case too high or too inflexibly, and a greater degree of care may be exercised in the preparation of expert witnesses’ reports.

In Australia, the doctrine of immunity for expert witnesses is still in place. The case of Commonwealth of Australia v Griffiths17 confirmed that the key objectives of the doctrine are to: (i) ensure that witnesses are able to give evidence freely; and (ii) avoid the same evidence being tried repeatedly in multiple actions. The Australian courts are, however, reluctant to give the protection of immunity a wide application. It is normally extends to include the taking of preparatory steps and preparation of statements and reports prepared outside of court, but it does not extend to the consideration of the expert’s conduct by the professional associations to which they belong.