Whose expert is the expert?

AnalysisThe problem every system faces is the same. Someone must explain a technical matter to a decision-maker who cannot assess it directly, and whoever explains it will have been chosen, instructed and paid by someone with an interest in the outcome. Left alone, that arrangement produces advocacy wearing a laboratory coat.

Germany takes the choice away. Section 73(1) of the Code of Criminal Procedure provides that die Auswahl der zuzuziehenden Sachverständigen und die Bestimmung ihrer Anzahl erfolgt durch den Richter — the selection of the experts to be consulted and the determination of their number is made by the judge — and that the judge should agree with them a period within which the reports can be delivered.

It then goes further than selection. Section 78 provides, in a single sentence, that the judge shall so far as it appears necessary direct the activity of the experts. And section 73(2) adds that where experts are publicly appointed for certain kinds of report, other persons should be chosen only where special circumstances require it.

The same structure appears in the death-investigation provisions. Under section 87 the autopsy is ordered by the judge, and it is performed by two physicians, one of whom must be a court physician or from a public forensic-medical or pathological institute. The examination is arranged by the court before anyone has an interest in its result.

England and Wales keeps party instruction and solves the loyalty problem directly. Rule 19.2 of the Criminal Procedure Rules provides that an expert must help the court to achieve the overriding objective by giving opinion that is objective and unbiased and within their area of expertise — and then, in terms: This duty overrides any obligation to the person from whom the expert receives instructions or by whom the expert is paid.

AnalysisTwo of those requirements do the heaviest work. Summarising the range of opinion forces an expert to disclose that competent people disagree, rather than presenting one view as the field’s. And providing what the court needs to judge reliability makes admissibility a question the report must help answer rather than one the expert may leave to advocates.

The obligations continue after the report. The expert must inform all parties and the court if their opinion changes from what a served report stated, and must define their area of expertise both in the report and when giving evidence in person.

• Common belief: Every system has experts instructed by the prosecution and the defence.

  In practice: German law places selection of the experts and determination of their number with the judge, and directs the judge to lead their activity so far as necessary. The phrase "the prosecution’s expert" describes an arrangement that system does not use.

• Common belief: An expert paid by one side is bound to favour it.

  In practice: Where parties do instruct experts, the rules can rank the loyalties. Rule 19.2(2) provides that the duty to the court overrides any obligation to whoever instructs or pays the expert — which does not make bias impossible, but does make it a breach of a stated duty rather than an understandable tendency.

• Common belief: An expert report is a statement of the scientific consensus.

  In practice: It is one expert’s opinion, and the rules require it to say so: where there is a range of opinion on the matters dealt with, the report must summarise that range and give reasons for the expert’s own view.

• Common belief: Whether expert evidence is reliable enough to admit is purely for the lawyers.

  In practice: The required report content includes such information as the court may need to decide whether the opinion is sufficiently reliable to be admissible. The expert is required to supply the material for that decision.

Two arrangements for the same problem.

• The judge selects the experts, sets their number and directs their activity — Germany, StPO §§ 73 and 78.
• A preference for publicly appointed experts where they exist for that kind of report — Germany, StPO § 73(2).
• Parties instruct, and the duty to the court overrides any obligation to whoever instructs or pays — England and Wales, CrimPR r. 19.2(2).
• A prescribed report content list, including range of opinion and the material the court needs to judge reliability — England and Wales, CrimPR r. 19.4.

AnalysisStated duties make expert evidence challengeable on grounds other than disagreement. A report that omits the range of opinion, or that fails to define the expert’s area of expertise, has departed from a requirement — which is a different objection from arguing that the conclusion is wrong.

AnalysisJudicial selection creates a different accountability, not less of it. Where the court chooses and directs the expert, the choice itself becomes part of the record and part of what an appeal can examine.

• Two systems are described from primary text — a code of criminal procedure and a set of procedural rules. Admissibility standards, remuneration, and how courts actually treat competing experts are not described.
• Nothing here describes civil proceedings, which have their own expert rules in both systems.

Related: what forensic science cannot decide, how forensic competence is established, who regulates forensic science, and what defence counsel does.