Former Supreme Court of Canada Justice Ian Binnie once remarked on the role of expert witnesses that "the courtroom ... is a poor school house and dueling experts may make bad teachers". 

The Ontario Energy Board (OEB) apparently sympathizes, having become one of the first administrative tribunals in Canada to introduce rules for expert witness "hot-tubbing". Hot-tubbing (less colloquially, termed "concurrent evidence") entails competing expert witnesses testifying together and being jointly questioned by the judge/tribunal, counsel and sometimes each other.

The OEB directed this novel arrangement last month in the Canadian Distributed Antenna Systems Coalition case and last week, permanently codified it in amendments to the Board's Rules of Practice and Procedure. The amendments stipulate, among other things, that the Board may require two or more experts to:

  • confer with each other in advance of the hearing for the purposes of narrowing issues, identifying points on which their views differ/agree and preparing joint written statements to be admissible as evidence at the hearing; and
  • appear together at the hearing as a concurrent expert panel for the purposes of answering questions from the Board and others and commenting on each other's views.

The practice of hot-tubbing originated in Australia and has incrementally spread to other jurisdictions – notably, it was recently incorporated into Canada's Federal Court Rules. 

Proponents of the practice say it increases efficiency by allowing adjudicators to more easily distil complex technical matters and pin down areas where experts differ. Perhaps, most importantly, proponents argue that it discourages experts from acting as advocates and overstating their opinions – Justice Binnie observed that "experts testifying in the presence of one another are likely to be more measured and complete in their pronouncements, knowing that exaggerations or errors will be pounced upon instantly by a learned colleague". 

Conversely, detractors argue that having competing experts testify together can devolve into a free for all and, far from reducing expert partisanship and advocacy, it may actually promote it by attaching less importance to expertise and placing a premium on experts' ability to out-debate their colleagues.

The OEB rule amendments are broad and will give OEB panels significant latitude in deciding how to employ this practice. Certainly, it will be of great interest to the sector – and other administrative tribunals in general - to see how this unfolds.

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