non compos mentis

[nohn kohm-pohs men-tis; English non kom-puh s men-tis] /ˈnoʊn ˈkoʊm poʊs ˈmɛn tɪs; English ˈnɒn ˈkɒm pəs ˈmɛn tɪs/
Latin.
1.
not of sound mind; mentally incapable of managing one's affairs.
British Dictionary definitions for non compos mentis

non compos mentis

/ˈnɒn ˈkɒmpəs ˈmɛntɪs/
adjective
1.
mentally incapable of managing one's own affairs; of unsound mind
Word Origin
Latin: not in control of one's mind
Word Origin and History for non compos mentis

Latin, literally "not master of one's mind."

non compos mentis in Medicine

non compos mentis non com·pos men·tis (nŏn kŏm'pəs měn'tĭs)
adj.
Not of sound mind and hence not legally responsible; mentally incompetent.

non compos mentis in Culture
non compos mentis [(non kom-puhs men-tis)]

A phrase used to describe someone who is out of his or her mind and therefore not legally responsible for his or her actions: “It was determined by the court that the killer was non compos mentis.” From Latin, meaning “not having control of the mind.”