Utah Code § 75-2-501: Who may make will -- Testamentary capacity.

(1) An individual may make a will if the individual:

(a) is 18 years old or older; and

(b) has testamentary capacity at the time that the will is executed.

(2) A testator has testamentary capacity under Subsection (1)(b) if the testator:

(a) can identify the testator's family members or other individuals in the testator's life;

(b) understands the testator's relationship to the individuals described in Subsection (2)(a);

(c) understands the nature and extent of the testator's property; and

(d) can form a plan in the testator's mind for the disposition of the testator's property.

(3) A testator is not required to have any knowledge or understanding of the laws of inheritance by intestate succession for the testator to have testamentary capacity under Subsection (2).

(4) There is a rebuttable presumption that testamentary capacity exists at the time that a will was executed even if the testator is subject to a guardianship or conservatorship or is otherwise unable to independently manage the testator's affairs.