What is expert evidence?

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. 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” and “a statement of his or her independence from the Parties, their legal advisors and the Arbitral Tribunal”.

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 pleadings” and to reduce “the … inappropriate use of experts to bolster cases”. 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”.

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”:

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