Sir Rupert Jackson has said that the role of experts is to confine themselves to the issues they have to opine upon; they have to express themselves clearly so that a layperson, including a judge, can understand it. They must be concise and must not be partisan. They are not advocates for parties. They are witnesses with a particular expertise who, due to an exception to the rules, are allowed to give opinion evidence.

In recent years, “hot-tubbing”, or “concurrent expert evidence” as it’s also referred to, has grown in popularity. It refers to the court process of calling expert witnesses to give evidence and be cross-examined concurrently. It involves the parties’ experts engaging in discussion together in the witness box and through this process, of expert challenging expert, a more accurate picture of the facts may emerge.

Hot-tubbing is a divisive issue, not least, because of an absence of any detailed guidance as to the optimal approach to hot-tubbing in international arbitration.

Although the International Bar Association (IBA) Rules on the Taking of Evidence in International Arbitration expressly provide for it, there isn’t much guidance on how to incorporate it into arbitrations.  Luckily, most institutional rules are sufficiently broad and allow it.

The increasing prevalence of experts directly challenging each other in international arbitration may inspire parties to find ways to adopt this principle sooner, before matters crystalise as a formal dispute.

Get in touch with us