Concurrent evidence has been described as “essentially a discussion chaired by the judge in which the various experts, the parties, the advocates and the judge engage in a cooperative endeavor to identify the issues and arrive where possible at a common resolution of them”: P McClellan, “New method with experts – concurrent evidence” (2010) 3 Journal of Court Innovation 259 at 264.

The legal framework governing the use of concurrent expert evidence in civil matters in NSW is set out in Pt 31, Div 2 of the UCPR. Rule 31.19 requires any party intending to call expert evidence at trial, or to whom it becomes apparent that they or another may adduce expert evidence, to promptly seek directions from the court. Unless the court otherwise orders, expert evidence may not be adduced at trial unless directions have been sought in accordance with r 31.19, and if any such directions have been given by the court, the expert evidence may not be adduced otherwise than in accordance with those directions: r 31.19(3). (Note that r 31.19 does not apply to proceedings with respect to a professional negligence claim: r 31.19(4).)

Rule 31.20(1) confers a broad discretionary power on the court in respect of the use of expert evidence in the proceedings. It provides: “Without limiting its other powers to give directions, the court may at any time give such directions as it considers appropriate in relation to the use of expert evidence in proceedings”.

Rule 31.35 makes specific provision for concurrent expert evidence. It relevantly provides that the court may give any one or more of the following directions:

It is customary for the experts to confer before they give evidence so as to refine the issues in dispute. Rule 31.24 facilitates this process. It relevantly provides that the court may at any time direct the experts: to confer, either generally or in relation to specified matters; to endeavour to reach agreement on any matters in issue; to prepare a joint report, specifying matters agreed and matters not agreed and reasons for any disagreement; and to base any joint report on specified facts or assumptions of fact. The court may direct that the conference be held with or without the attendance of the parties or their legal representatives; with or without the attendance of the parties or their legal representatives, at the parties’ option; or with or without the attendance of a facilitator (that is, a person independent of the parties and who may or may not be an expert in relation to the matters in issue): rr 31.24(2)(a)–(c). Unless the parties agree, the content of the conference between the expert witnesses must not be referred to at any hearing: r 31.24(6). Expert witnesses directed in accordance with r 31.24 may apply in writing to the court for further directions to assist the expert witness in the performance of his or her functions in any respect: rr 31.24(3)–(4). An expert witness who makes such an application must send a copy of the request to the other expert witnesses and to the parties affected: r 31.24(5).

Concurrent and consecutive expert evidence in criminal trials is dealt with by s 275C of the Criminal Procedure Act 1986.

Aside from efficiency gains, concurrent evidence tends also to improve the quality of the expert evidence available to the decision-maker. The experts give their opinions free from the constraints of the adversarial process, and are not limited to answering questions from counsel. They are thus able to present their views comprehensively, without distortion by the advocate’s skill: P McClellan, “New Method with Experts – Concurrent Evidence”, at 266. As the experts are able to respond directly to each other, each of their opinions comes in for rigorous testing by their peers. Often the experts will ask each other incisive questions that would not have occurred to counsel. The judge is therefore better placed to determine which of the expert opinions should be accepted: see, for example, Halverson v Dobler [2006] NSWSC 1307 at [67].

The New South Wales Court of Appeal has considered the use of concurrent evidence in the context of determining the point at which judicial intervention has the effect of denying the parties procedural fairness. In Botany Bay Council v Rethmann Australia Environmental Services Pty Ltd [2004] NSWCA 414, Tobias JA (Spigelman CJ and Santow JA agreeing) held at [46] that interventions from the judge are permissible to the extent that their purpose is to clarify the experts’ evidence, rather than to cross-examine the witnesses or challenge their evidence. Particularly in matters where a judge sits without a jury, “the judge may intervene to control, to clarify, or to make known a provisional view”: Botany Bay Council, above, at [43], quoting Kekatos v The Council of the Law Society of New South Wales [1999] NSWCA 288 at [60] (Giles JA).

The General Case Management Practice Note of the Supreme Court, Common Law Division 5 (PN 5), as amended, mandates the presumptive use of concurrent expert evidence in all proceedings in which a claim is made for damages for personal injury or disability. Paragraph 37 provides, in respect of such proceedings: “All expert evidence will be given concurrently unless there is a single expert appointed or the court grants leave for expert evidence to be given in an alternate manner”. The rationale for the presumptive use of concurrent expert evidence is set out at [32] of PN 5, which recites the court’s concern about the costs and delays associated with the large number of experts expected to give evidence in personal injury cases. The court is particularly concerned to avoid overlap between expert opinions as well as the expenses associated with expert reports that go unused or are otherwise of little assistance to the court.

Paragraph 38 of PN 5 explains the procedure for deciding between the use of a single expert and the use of multiple experts. It provides: “At the first Directions Hearing the parties are to produce a schedule of the issues in respect of which expert evidence may be adduced and identify whether those issues potentially should be dealt with by a single expert witness appointed by the parties or by expert witnesses retained by each party who will give evidence concurrently”.

If expert evidence is to be given concurrently, the parties are to agree on the issues to be discussed by the expert witnesses within 14 days of all expert witness statements or reports being filed and served. If the parties are unable to reach agreement within the 14-day period, they must arrange for the matter to be re-listed before the court for directions as to the issues to be discussed by the expert witnesses: PN 5, at [39].

To refine the issues in cases where expert evidence is to be given concurrently, the experts in each area of expertise are to confer and produce a report, with respect to the issues to be discussed by them, setting out a statement of matters agreed and matters not agreed (see also UCPR r 31.25). With respect to matters not agreed, short reasons should be provided as to the basis of the disagreement. Such a report should be produced within 35 days of the first Directions hearing or such other time as the court may order: PN 5, at [40].

The PN 5 should be read alongside Practice Note SC Gen 11 (Joint Conferences of Expert Witnesses). Paragraph 8 provides that the issues to be discussed by the experts should be framed to resolve a controversy in the proceedings. If possible, the issues so identified should be capable of being dealt with by way of a brief response. The Practice Note also makes provision for how the joint conference is to be convened and conducted (at [12]–[24]), as well as how the joint report is to be prepared: at [25]–[29]. It emphasises throughout that the experts must comply with the Expert Witness Code of Conduct set out in Sch 7 to the UCPR and made binding on experts by r 31.23.