The Medicolegal Implications of Functional Neurological Disorder

Abstract: Functional neurological disorder (FND) commonly arises in the context of injury, trauma, or litigation and poses distinctive medicolegal challenges. This review outlines how positive clinical signs and contemporary neurobiological models support FND as a robust diagnosis, while distinguishing it from factitious disorder and malingering. We discuss approaches to assessing authenticity of reported disability, the role and limitations of symptom and performance validity tests, and the pitfalls of equating inconsistency with deception. We then consider causation within common legal frameworks using a predisposing-precipitating-perpetuating model to analyze the contribution of index events, background vulnerabilities, and the litigation process itself. Finally, we summarize current evidence on treatment and prognosis, highlighting the limits of prediction and the need to offer courts transparent, probabilistic opinions on long-term outcome and care needs. Our aim is to support clinicians in providing balanced, clinically grounded expert evidence for patients with FND.