Control specialist evidence: anonymity and experts

Anonymity is a restriction on identification, not a credibility finding. A witness anonymity orderGlossary termWitness anonymity order under Coroners and Justice Act 2009, ss 86–90, may permit a pseudonym, conceal identifying details, restrict identifying questions, or provide specified screening or voice arrangements. It is different from a screen which merely prevents seeing the accused, a restriction on publication, or practical witness protection. Section 86 does not authorise hiding the witness's appearance or natural voice from the judge and jury.

All three conditions must be satisfied. Under s 88, the proposed measures must be necessary to protect the safety of the witness or another person, prevent serious property damage, or prevent real harm to the public interest. Their effect must be consistent with a fair trial. Finally, the testimony must be important enough that the witness ought to testify in the interests of justice, and either the witness would not testify without the order or testimony without it would cause real public-interest harm. A request for anonymity, or the prosecution's wish to secure useful testimony, does not alone meet these conditions.

Necessity must be tested against the defence's ability to challenge. Under s 89, consider the general right to know a witness's identity, the importance of credibility, whether the evidence could be sole or decisive, whether it can be properly tested anonymously, dishonesty or motive to lie, and reasonably practicable alternatives. Sole-or-decisive evidence is an express consideration, not a substitute for the complete statutory assessment. A threat does not override the fair-trial condition. If a less restrictive arrangement protects the witness while permitting proper testing, explain why full anonymity is unnecessary.

Procedure protects both identity and scrutiny. Prosecutor or defendant may apply under s 87, using CrimPR rr 18.14–18.18. The applicant must explain the measures, conditions, supporting evidence and necessary withholding of material. The court must have the information needed to test the application; identity must not be circulated indiscriminately merely to make the application. The parties must have the lawful opportunity to make representations, and the court considers the restrictions on disclosure and attendance. Reasons must not defeat the protection being considered. The order remains subject to variation or discharge under s 91. In a jury trial, s 90 requires an appropriate warning to prevent the order prejudicing the accused. CPD para 6.6.

Expert evidence provides specialised assistance. An ordinary witness usually describes observed facts. Expert evidenceGlossary termExpert evidence offers an opinion based on specialised knowledge or experience. Under CrimPR Part 19 and CPD para 7.1.1, it must be relevant, needed on a matter outside the court's unaided knowledge and experience, given by a competent expert, and sufficiently reliable to be admitted. The competence of an expert in this sense includes expertise in the particular field; it is not merely the general communication test for witnesses.

An impressive title is not a reliable method. Examine the data, assumptions, testing, uncertainty, relevant peer scrutiny and whether the method was properly applied in this case. The expert must explain the reasoning from findings to conclusion, including material limitations and any range of responsible opinion. An assumption supplied by an instructing party is not thereby proved. Admissibility is for the judge; the tribunal of fact decides what weight the admitted opinion deserves. CPD paras 7.1.1–7.1.3; CrimPR r 19.4.

The duty is to the court, not the payer. Under r 19.2, opinion must be objective, unbiased and within the expert's expertise. The expert must identify matters which could undermine the opinion or credibility and must notify the parties and court if the opinion changes from that in the served report. A report under r 19.4 identifies qualifications, material relied on, factual sources, work done by others, methods, conclusions, qualifications to the opinion and the required declarations. Selecting only favourable results is inconsistent with this duty.

Service is not optional. Under r 19.3, the party wishing to rely on expert evidence must serve the required report or permitted summary and supporting information as soon as practicable; underlying examination and test records must be made available as the rule requires. The rule also requires notice of material capable of undermining the opinion's reliability, credibility or impartiality. The court controls non-compliance and whether the evidence can be introduced. Where the expert will not give oral evidence, do not assume that filing the report settles admissibility: apply Criminal Justice Act 1988, s 30, including the requirement for the court's leave when the author is not called.

Resolved criticism may still need disclosure. Under CPD paras 7.1.3–7.1.5, material warnings about a technique, adverse judicial comment, disciplinary or regulatory criticism, and relevant problems affecting an expert's organisation must be addressed. The current direction expressly includes criticism which has since been resolved, such as by a Forensic Science Regulator completion certificate. Resolution can affect the explanation and weight; it does not automatically erase the disclosure issue. Expert discussions and joint statements under r 19.6 identify genuine agreement and disagreement, not positions dictated by those instructing the experts.