Assessing Attachment Disorder in Group Litigation: The Expert’s Evidence Requirements

The Medico-Legal Challenge of Attachment in Group Claims

In group litigation involving institutional settings, the assessment of psychological sequelae often involves shifting from individualised symptomology to the systemic evaluation of developmental outcomes. When claimants allege that failures in duty of care led to chronic attachment disruption, experts must distinguish between transient adjustment reactions and enduring clinical presentations related to reactive attachment disorder. This requires precision in separating pre-existing vulnerabilities, constitutional factors, and the specific impact of the alleged institutional environment.

Clinical Methodology and Evidence Requirements

Experts in group litigation must address the challenge of longitudinal assessment. Many claimants in group actions report historic abuse where the index events occurred decades prior. Under the Limitation Act 1980, the court’s discretion under Section 33 to allow claims out of time often hinges upon the reliability of expert evidence regarding the claimant’s psychological capacity to recognise and report harm. Psychiatry Experts’s guidance on reactive attachment disorder examines the same instruction questions in more depth.

Clinical assessments in this context typically integrate:

• Detailed developmental histories, triangulated with school, local authority, and social services records where available.
• Application of validated psychometric tools, whilst acknowledging the limitations of these tools in retrospective forensic settings.
• Analysis of ‘Disturbances in Self-Organisation’ (DSO) under the ICD-11 framework, which some experts find provides a useful lens for adult claimants.
• Analysis of ‘betrayal trauma’ theory, which may assist the court in understanding delayed disclosure in institutional contexts.

Legal Procedural Considerations

The role of the expert witness in group litigation is governed by the Civil Procedure Rules (CPR). Instructing solicitors should distinguish between the various procedural mechanisms available:

• CPR 35.7 and 35.8: Where the court directs the instruction of a single joint expert (SJE) under CPR 35.7, the expert’s overriding duty to the court (CPR 35.3) remains paramount. The expert must remain independent, regardless of the funding arrangement. Instructions to an SJE are governed by CPR 35.8.
• CPR 35.12: This governs the process of expert discussions. Where multiple experts are instructed by different parties, the court may direct them to engage in discussions to identify the issues on which they agree and disagree, and to produce a joint statement to narrow the issues for the court.
• CPR 35.10: Expert reports must clearly state the substance of all material instructions and detail the range of opinion on significant clinical questions.

Common Pitfalls in Complex Claims

A risk in group litigation is the tendency to assume a homogenous psychiatric presentation across a cohort. Medico-legal experts must maintain focus on individual causation. Following the principles of Armes v Nottinghamshire County Council [2017] UKSC 60 regarding vicarious liability and non-delegable duty, the clinical evidence must link specific failures of care to the individual claimant’s developmental trajectory.

Robust reporting generally includes:

• The ‘eggshell skull’ principle: acknowledging that a claimant may have been particularly vulnerable to injury without necessarily having a pre-existing diagnosable condition.
• Symptom validity: considering the use of tools such as the Test of Memory Malingering (TOMM) or the Structured Inventory of Malingered Symptomatology (SIMS) when there is a risk of inconsistency, noting that these are subject to forensic scrutiny.
• The potential impact of secondary victimisation resulting from the litigation process itself.

Practical Guidance for Instructing Solicitors

To ensure a report is of maximum utility, instructing solicitors should facilitate a comprehensive document disclosure process. Primary records from the alleged period of abuse are critical for addressing the ‘but-for’ causation required in civil negligence. When drafting letters of instruction, ensure the expert is directed to address the legal tests for causation applicable to the specific claim, rather than seeking a purely clinical narrative.

Multi-disciplinary input is often required where the claimant presents with complex physical and psychiatric injuries. Engaging a team—such as a child psychiatrist for historical perspective and a clinical psychologist for assessment of current functioning—can provide a more comprehensive, court-ready analysis. The expert must remain the sole arbiter of their clinical opinion; the expert’s duty under CPR 35.3 precludes modifying conclusions based on party pressure.