Charrett, D., and potts, A.E. (2012). Inhouse Counsel, 266, 15(8). July 2012.


While it is now normal practice in litigation and arbitration for the evidence-in-chief of technical experts to be given in the form of written expert reports, this may not always be the best way of communicating complex technical issues to the tribunal which has to decide between conflicting opinion evidence. This paper reviews modern approaches to the evidence of experts, and suggests that the written reports may need to be supplemented by an appropriately prepared oral presentation to better convey the full technical complexity and implications thereof to the tribunal.

In any litigation or arbitration on disputes with "technical" issues that are not within the common knowledge of the judge or arbitrator (the tribunal), expert evidence is essential to assist the tribunal in understanding the relevant facts. Unlike other witnesses of fact (lay witnesses), a properly qualified expert is permitted to give opinion evidence within the scope of their expertise and field of knowledge. 

In Australian litigation or arbitration, it is normal for the opposing parties to engage their own experts. The universal position is that each expert owes a paramount duty to assist the tribunal, and that they are not an advocate for the party that engaged them. Notwithstanding this paramount duty, the traditional use of "opposing" experts is not without its problems. These include:

  • Not all experts are equal — in the relevant field of knowledge, in expertise, in technical or witness experience or in oral or written communication skills;
  • Some experts are "hired guns" who have a reputation of providing opinions that are invariably favourable to the party that engaged them;
  • The briefs to opposing experts may not address the same issues and questions, or may specify a different set of factual assumptions;
  • The experts may be inappropriately briefed with material that prejudices their objective view of the facts and the issues;
  • The experts may not fully comprehend what their paramount duty to the tribunal entails.

The modern approach to the use of experts in complex disputes is based on a number of techniques that attempt to address these problems. These techniques may involve some or all of the following:

  • Written expert reports used as evidence-in-chief at the hearing;
  • An "expert conference" prior to the hearing at which the opposing experts meet to discuss any differences between them and endeavour to reach common ground;
  • A common brief to all experts, jointly prepared by the lawyers acting for the opposing parties, detailing a common set (or alternative sets) of facts on which the experts' opinions are to be based;
  • Concurrent expert evidence in the hearing, colloquially referred to as "hot tubbing".

Some issues that may arise from these techniques are discussed in the following sections.