Defining “mental disorder” in legal contexts

Despite its widespread use, the term “mental disorder” has proven remarkably difficult to define. This is of grave concern in those legal contexts which crucially depend on the classification of an individual’s mental health condition as a “mental disorder”. It creates a likelihood that individuals will be treated in an inconsistent and unprincipled fashion, which is unacceptable in a legal system which purports to operate under the rule of law. This article examines the way in which the term “mental disorder” should be defined in legal contexts. It critiques the approach taken by the two main psychiatric manuals currently in use (the DSM-5 and the ICD-10), as well as three suggested alternatives: Boorse’s biostatistical theory; Wakefield’s harmful dysfunction theory; and Jaspers’ lack of meaningful connections approach. It recommends the adoption of a context-specific, purpose-based approach that focuses on the normative concerns of the law.