non compos mentis

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The Latin non compos mentis translates as “not of sound mind.”  In the 1928 Hellman Commercial Trust & Savings Bank v. Alden opinion, the Supreme Court of California stated that the term’s legal usage encompassed “all degrees of mental incompetency known to the law” and compared it to the Standard Dictionary definition of an “unsound mind.”  In specifying the term’s legal scope, the Court of Civil Appeals of Alabama, in the 1985 Goza v. Goza holding, noted that “[m]ere emotional instability or depression” does not qualify as non compos mentis, and that while the term “does not necessarily denote a total destruction of the intellect, … there must be at least such a severe impairment of the mental faculties as to make the movant incapable of protecting himself or of managing his affairs.”  The United States Court of Appeals of the District of Columbia Circuit provided a similar definition in the 1998 Smith-Haynie v. District of Columbia opinion to clarify the term’s meaning, as found in Section 12-302 of the Code of the District of Columbia. The court wrote that the disability of a person claiming to be non compos mentis must be “of such a nature as to show [she] is unable to manage [her] business affairs or estate, or to comprehend [her] legal rights or liabilities.”

[Last updated in June of 2020 by the Wex Definitions Team]