(3) The expert’s report must state the substance of all material instructions, whether written or oral, on the basis of which the report was written.

(4) The instructions referred to in paragraph (3) shall not be privileged against disclosure but the court will not, in relation to those instructions –

(a) order disclosure of any specific document; or

(b) permit any questioning in court, other than by the party who instructed the expert,

unless satisfied that there are reasonable grounds to consider the statement of instructions given under paragraph (3) to be inaccurate or incomplete.

Basic conundrum: experts needed to assist court in understanding complex technical/scientific material which requires expertise courts lacks — how is court to assess the reliability of competing expert evidence?

Broadly three main categories of issues with expert evidence:

• (1) Costs: expert evidence has main driver of high costs of litigation

  • Systems or devices to reduce costs: court control of expert evidence (CPR Rule 35.4) and costs estimates and capping (CPR Rule 35.4)

• (2) Due process: concern whether expert, in practice, is a witness or a judge — See Mantovelli

• (3) Probative value: concerns that expert evidence susceptible to multiple forms of bias

CPR adopted three important measures to address particular problem of “cultural of partisanship” within expert evidence:

• (1) No party may reply on expert evidence without court’s permission (and court controls number and nature of experts) (CPR 35.4(1))

• (2) Expert’s primary duty is to help the court arrive at a correct decision on matters within expertise (CPR 35.3(1))

• (3) Rules seek to promote party co-operation in experts and to encourage use of joint experts

Admissibility of expert evidence:

• England: Admissibility bar “not particularly high” — admissible where:

  • (b) there is an acknowledged “body of expertise” (ie. field governed by established principles and rules); and

  • (c) court considers that expert evidence would assist in the determination of the issues

• Cf. United States: focus on admissibility — because of Constitutional entitlement to a jury (consider weight of evidence) judge as the gatekeeper on what gets through to the jury for consideration — Daubert [See case notes below]

• After admission, Court to decide weight given to expert testimony: no power to delegate judicial role— court must decide issues (ie. not bound to follow expert)

  • If conflicting expert testimony, must set out coherent reasons for accepting evidence of one

  • No rule of law requiring court to favour expert testimony where conflicting with witness of fact

Expert Role/Duties:

• CPR 35.3: expert’s primary obligation is to the court:

  • Duty of experts to help the court on the matters within their expertise.

  • This duty overrides any obligation to the person from whom experts have received instructions or by whom they are paid.

• While all witnesses under duty to tell the truth, difference between experts and other witnesses makes it necessary to stress that experts must serve the court:

  • (i) retained because they can advance party’s case through production of evidence (cf. chosen for fact of witnessing)

  • (ii) seek to influence outcome by advancing explanatory theories (cf. merely report based on observation)

  • (iii) paid for their evidence (service for profit)

  • Thus: CPR 35.3 designed to counteract partisan tendencies— buttressed by CPR 35.10(2): experts to state in report that they understood/complied with duty

• Duties divided into two categories:

  • (A) Impartiality: expert to reach conclusion in accordance with evidence/conformity with rules governing subject, regardless of whether conclusion satisfies client

  • (B) Transparency: expert reports should be comprehensible, clearly indicate underlying assumptions, reasons for conclusions, and any doubts that may remain

• Impartiality goes to probative weight, not admissibility

  • HOWEVER: Where close personal relationship between expert and client which reasonable observer might think capable of affecting expert’s views so as to make them unduly favourable, evidence should not be admitted, however unbiased conclusions might be (Liverpool Roman Catholic Archdiocese Trustees)

  • Given decoupling of apparent bias test from expert admissibility, crucial that court be made aware of influences on expert (ie. direct financial interest; employee or other continuing relationship etc) (Factorame) — only if court informed can it consider whether appropriate to allow expert to testify and weight of evidence

• Note: Transparency more important than independence — enables the opponent and court to take account of any lack of independence f

Court’s power over expert evidence

• (a) Court permission required for using expert evidence (CPR 35.4)

  • Court to determine nature of expert evidence and way it is to be placed before court — ensure that evidence adduced in most effective/economic way consistent

  • Expert evidence restricted to that which is reasonably required to resolve the proceeding (CPR 35.1)

• (b) Limiting the number of expert witnesses

  • Equality of arms requires each party be given permission to call same number of experts (although requirement should not be taken too literally)

• (c) Application to change expert or call additional expert

  • Permission only granted upon showing good reasons and may be conditional

  • Only in exceptional circumstances allow party to instruct fresh expert without disclosing previous report (deter “expert shopping”: Beck; Edwards-Tubb)

  • Difficulty where party wishes to disavow expert because expert conceded opponent’s case

    • Party must demonstrate...