Capacity to benefit under a will
The following persons are disqualified from benefitting under a will:
1. A person who has unduly influenced the person who wrote the will (the testator or testatrix) to give him a benefit under the will.
2. A person who is unworthy, e.g.
a. A person who unlawfully has caused the death of the testator. This is in accordance with the maxim de bloedige hand er neemt geen erffenis, and clearly the person who murders another cannot take a benefit from the will of his victim.
In Makhanya v Minister of Finance the court used the de bloedige hand maxim to extend the rule to cover any proceeds from the deceased’s pension fund from benefiting the person who caused the deceased’s death.
b. a person who has led another into an immoral life and indirectly caused the latter’s death;
c. a person who has concealed the will of the testator;
d. A person who has attempted to defraud persons of their rightful inheritance by forging a will.
Whether a person is unworthy to receive a benefit is a relative question vis-à-vis the actions of the potential beneficiary towards a particular testator. The fact that the potential beneficiary may generally be of unsavoury character does not per se disqualify him, unless he has conducted himself badly or ill-treated a particular testator from whom he expects to receive a testamentary benefit.
The facts in Danielz NO v De Wet and Another, De Wet v Danielz NO and Another  4 All SA 549 (C) were that De Wet was the sole nominated beneficiary under four life insurance policies on the life of her late husband. In 2000, she hired and paid two men to assault her husband. Unfortunately, they killed him.
In 2006, after the she had been convicted on the criminal charges against her, she claimed under the life insurance policies from the insurer. The applicant, who was the nominee of the insurer (Old Mutual), applied for a declaratory order that De Wet was not entitled to the proceeds of the life insurance policies.
The court agreed and the application for a declaratory order to bar De Wet from claiming the proceeds of the policy was therefore successful.