Adult psychology experts in UK legal proceedings — what solicitors need to know

Role and duty to the court
Registered psychologists provide independent opinion evidence on mental functioning, trauma and cognitive abilities (e.g., memory, suggestibility, executive function). Their overriding duty is to the court, not the instructing party, and their evidence is controlled by the relevant procedural codes: CPR 35 in civil claims, CrimPR 19 in criminal cases, and FPR 25 in family proceedings. These frameworks restrict expert evidence to what is necessary and prescribe report content and declarations.  

Criminal courts (Magistrates’ and Crown Court)
Adult psychologists commonly assess: (1) capacity to participate, including attention, comprehension and decision-making; (2) vulnerability (learning disability, neurodivergence, mental disorder, PTSD); (3) reliability of testimony (e.g., suggestibility, false confession risk); and (4) mitigation and risk in sentencing. They assist the court on fitness to plead / fitness to stand trial, applying the Pritchard criteria as reflected in CPS guidance, and may advise on adaptations (intermediaries, ground rules hearings, written aids) under CrimPR measures to assist participation. Reports must meet CrimPR Part 19 requirements and the expert’s duty of impartiality.  

Family Court / Family Division (adults only)
Psychologists are instructed to evaluate adult parties on parenting capacity, mental functioning relevant to safeguarding, domestic abuse dynamics (including coercive control), treatment prospects, and the impact of trauma on decision-making. Court permission is mandatory and the Family Procedure Rules favour single joint instruction where proportionate, with detailed requirements for letters of instruction and reports (PD 25 series). The Bond Solon family procedure materials summarise the family court structure and expert controls practitioners should expect.  

Civil courts (County Court / High Court)
In personal injury, clinical negligence and workplace stress claims, psychologists opine on diagnosis, causation, severity and prognosis of psychiatric injury; administer and interpret psychometrics; and advise on rehabilitation. Use of experts is confined to what is “reasonably required” (CPR 35) and best practice follows the Judicial College Guidance for the Instruction of Experts in Civil Claims (report structure, statements of truth, disclosure of range of opinion).  

Asylum and Immigration (First-tier Tribunal & Upper Tribunal, IAC)
Psychologists provide medico-legal evidence on trauma (e.g., PTSD, depression), memory fragmentation, functional impairment, and risk on return. The IAC’s Practice Direction (Nov 2024) sets expectations for expert evidence, bundles and witness statements; parties should ensure opinion stays within expertise, reasons are given, and sources are identified. Vulnerability and participation needs should be highlighted with recommended adjustments for the hearing. 

Instruction via the Expert Witness Gateway (EWG)
Psychology is a supported specialty on EWG. Case types include criminal, civil, clinical negligence and care/family, with LAA, private, local authority, police and insurance funding options. The platform’s workflow supports court approval where required, single-joint or sole instruction, and staged addenda or court attendance. EWG provides clear case timelines (from enquiry and LOI to report, addendum and attendance) and keeps funding breakdowns hidden from the expert; invoices flow through the portal. Experts and solicitors must keep substantive communications on-platform and comply with CPR/FPR/CrimPR; EWG terms reinforce confidentiality, non-circumvention and payment mechanics (including trust arrangements for privately funded matters).

What to include in your instructions

• Procedural posture, the legal questions the court must answer, and the rule-set (CPR 35 / CrimPR 19 / FPR 25).  
• Specific issues of participation or vulnerability and any measures sought.  
• Full disclosure (clinical, occupational, educational records) and a neutral chronology.
• Scope, timescales and funding route (LAA/private), aligned to EWG’s quoting and approval process.

Used well, adult psychology evidence helps the court resolve necessity-driven questions about functioning, reliability and risk, while remaining squarely within the expert’s duty to assist the court.