Also known as: sound mind · of sound mind
Written by attorneys · grounded in primary & secondary sources — see below
A condition of mental soundness in which a person understands the nature and consequences of legal acts. This capacity is required to execute a valid will under statutes providing that an individual eighteen or more years of age who is of sound mind may make a will.
Sarah Sullivan, age forty-two, sat at her kitchen table and signed a typed document disposing of her home and savings to her two children. Two neighbors of sound mind witnessed the signing and confirmed that Sarah understood the document's purpose and the extent of her property. Because Sarah was sanae mentis at the time of execution, the will satisfied the statutory requirements for validity.
Spencer Silver stood trial for murder after evidence showed he had acted with deliberate intent during the incident. The prosecution introduced testimony establishing that Spencer was sanae mentis both before and during the events, allowing the jury to infer the required mental state from his actions without shifting any burden to the defense.
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Samuel Soto lay in a persistent vegetative state after an accident, and his family sought to discontinue life support. The court required clear evidence that Samuel had previously expressed wishes while sanae mentis, because no formal advance directive existed and the state demanded reliable proof of his prior competent intent.
Samantha Stone consulted a surgeon about a risky procedure and signed a consent form after receiving detailed explanations. The physician documented that Samantha was sanae mentis and fully understood the risks and alternatives, satisfying the legal prerequisite for a valid consent that later shielded the doctor from a battery claim.
Seth Shapiro was charged with assault and raised an insanity defense at trial. Expert testimony established that Seth suffered from a mental disease that prevented him from appreciating the wrongfulness of his conduct, so the jury found he was not sanae mentis at the time of the offense and returned a verdict of not guilty by reason of insanity.
Skylar Sullivan, terminally ill and still sanae mentis, sought a physician's assistance to end her life under a state statute. The court upheld the statute's prohibition, holding that the state's interest in preserving life outweighed the claim of a competent adult to assistance in dying even when the patient remained of sound mind.
The phrase requires that the testator understand the nature and extent of property, the natural objects of bounty, and the disposition being made. Under the Uniform Probate Code, an individual eighteen or older who meets this standard may execute a will. Failure to satisfy the standard renders the instrument void.
Yes. Witnesses must be generally competent adults of sound mind capable of observing, recalling, and testifying about the execution. An interested beneficiary who meets this standard may validly witness the will without invalidating it or the gift.
A minor lacks capacity to make a will regardless of actual mental soundness. The rule treats anyone under the statutory age as lacking the required legal capacity even if the individual otherwise demonstrates understanding.
…however, the trust company, pursuant to the requirements of § 100-c (9), had notified by mail each person of full age and sound mind whose name and address were then known to it and who was "entitled to share in the income therefrom. . . [or] . . . who would be entitled to share in the principal if the event upon which…