In the British jurisdiction of England and Wales the Lunacy Acts 1890-1922 referred to "lunatics", but the Mental Treatment Act 1930 changed the legal term to "person of unsound mind", an expression which was replaced under the Mental Health Act 1959 by "mental illness".
"Of unsound mind" or non compos mentis are alternatives to "lunatic", which was the most conspicuous term used for insanity in the law in the late 19th century [REF].