In common law, individuals have the right to make a will given their sound mental and legal ability to be able to do so. This capacity given to them by law is referred to as testamentary capacity. It assures that an individual who makes a will is in possession of the appropriate mental and legal abilities necessary to write such a will.
It is common for beneficiaries who are not satisfied with the portion of the estate given to them to contest the validity of a will by citing the lack of mental or legal ability the deceased had in making the will. The aforementioned beneficiaries often charge the testator, or individual who has written the will, with senility, insanity, or some other condition that proves a lack of reasonable, mental faculty.
In order to prove testamentary capacity to be valid, the courts must be given proof that the testator was aware of the value and extent of his or her estate, the beneficiaries of such an estate, the will he or she is writing, and the process upon which the estate is to be disbursed to its beneficiaries by virtue of the will.
The burden of proof lies with the disgruntled heirs who feel that they deserve more than what has been apportioned to them. In order to prove that the testator lacked testamentary capacity, the heirs must provide evidence of lack of mental and legal ability. Both elements that comprise testamentary capacity need to be disproved in order to contest the validity of a will.