Also known as: mental incompetency · mentally incompetent · mentally incompetent person · incapacity · mental incapacity · incompetence
Written by attorneys · grounded in primary & secondary sources — see below
A condition in which a person lacks sufficient mental capacity to understand the nature and consequences of a legal act or to act reasonably in relation to it.
Select any source to read its text and confirm it supports the definition.
Maria Morales mailed an offer to sell her warehouse to Maurice Marshall. Before Maurice could accept, Maria suffered a stroke that left her unable to manage her affairs. Maurice's attempted acceptance two weeks later produced no contract because the offer had terminated.
Michael Miller granted his accountant power to manage rental properties. After Michael was diagnosed with advanced dementia and placed under guardianship, the accountant continued signing leases. The new guardian successfully challenged those leases as unauthorized.
Mustafa Mahmoud executed a durable power of attorney naming his daughter as agent for financial decisions. When Mustafa later developed Alzheimer's disease, the daughter continued paying bills and selling assets. The transactions remained valid because the power was durable.
Melissa Mills, while heavily medicated after surgery, signed a consent form for an experimental procedure. The physician performed the procedure relying on the form. Melissa later sued for battery, claiming she lacked capacity to consent at the time.
Mohan Malhotra fathered a child out of wedlock but suffered a traumatic brain injury before the child turned two. He never resided with or supported the child. A court later treated the child as his for class-gift purposes because incapacity had prevented him from functioning as a parent.
A sitting judge repeatedly directed guilty verdicts in criminal cases and failed to advise defendants of appeal rights. The judicial council found the pattern constituted gross incompetence and removed the judge from the bench.
Mental incompetence of the offeror or offeree terminates the power of acceptance under the same rules that govern death of a party.
Supporting sources
Loss of capacity by the principal has the same effect on the agent's authority as the principal's death during the period of incapacity.
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A power of attorney is durable when it is not terminated by the principal's incapacity.
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The rules governing incapacity to consent apply to intentional invasions of interests of personality.
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…in a mental hospital for his own welfare and protection or the protection of others, and if so “(3) whether he is mentally incompetent.” Art. 5547-51 (Vernon 1958). The trial on these issues extended over six days. The State offered evidence that appellant suffered from serious delusions, that he often had threatened to…