지적능력이 저하된 사람의 유언 ― 대법원 2022. 12. 1. 선고 2022다261237 판결에 대한 평석을 겸하여 ―

In the case under review, a petition for the commencement of adult guardianship was filed, and a temporary guardian for the decedent was appointed as a preliminary measure. However, since the decision on the guardianship had not yet been finalized, the validity of a will made by the decedent, who was a person with dementia, without the consent of the temporary guardian became an issue. Because this involves a legal act by a dementia patient whose mental capacity may be in doubt, the presence or absence of such capacity becomes an issue. In particular, as a special form of legal act, a will requires the testator’s mental capacity, that is, testamentary capacity. Although there is no explicit statutory provision addressing this, established academic theories and case law appear to have evaluated mental capacity and testamentary capacity in a similar manner. Judgments addressing mental capacity in individuals with diminished intellectual abilities, such as the elderly, the seriously ill, or persons with dementia, are mostly related to wills. An analysis of relevant Supreme Court and lower court decisions reveals that, in practice, mental capacity and testamentary capacity are not clearly distinguished. Therefore, extracting specific criteria for testamentary capacity alone is virtually impossible, as such criteria must be considered in conjunction with mental capacity or with formal requirements for wills. In this context, a review of the present case shows that the court held that the decedent could freely execute a will as long as they possessed mental capacity. However, the court appears to have conflated testamentary capacity with mental capacity, or to have treated one as the basis for evaluating the other. While the conclusion of the court is agreeable in light of the fact that the most important aspect of a will is respect for the right to self-determination, it is somewhat regrettable that there was no detailed examination of testamentary capacity and no specific reasoning provided for recognizing the decedent’s mental capacity.