The capacity requirement to execute a will is a minimal standard, it is lower than the requirement for other legal documents: less capacity is required to enable one to make a will than to make other contracts.
Capacity is evaluated by three factors: whether decedent understood the nature and consequences of executing a will, whether she knew the nature and extent of the property she was disposing of, and whether she knew those who would be considered the natural objects of her bounty and her relations with them.
The proponent of the will bears the burden to prove testamentary capacity at trial.
Once a proponent makes a prima facie case for probate, the burden switches to the objectant to show a triable issue of fact. There is a presumption of testamentary capacity when a will is drafted and the execution is supervised by an attorney, particularly when the evidence indicates that the testator executed the will only after careful review and discussion of its contents.