Assessing concurrent expert evidence

Concurrent expert evidence or hot tubbing takes a variety of forms, which depart from the conventional presentation of evidence by having experts called by different parties give their evidence together and/or directly question one another. Amendments recently approved to CPR 35.11 following the Civil Justice Council (CJC) review of concurrent evidence aim to ‘steer’ the courts towards greater use of a judge-led form of hot tubbing. This article reviews what is known about concurrent evidence in UK jurisdictions, and in particular what can be gleaned from published judgments in cases where it has been used. The evidence for the effectiveness of such procedures is largely anecdotal and impressionistic, and much of it relates to specialist courts and tribunals where factfinders have some degree of expertise in the witnesses’ field. While not disputing that concurrent evidence can work well when skilfully employed, we question whether enough is known to justify a widespread extension of judge-led concurrent evidence to generalist civil courts.