This is a difficult question. Some people may be ill or elderly at the time they make a will. They may not be able to understand their finances in the same way as a “normal” person in their position. They may not be able to understand the effect of the will they are making.
A will is only valid if the will maker has “testamentary capacity” at the time he or she made the will. To have testamentary capacity, the will maker has to:
When wills are made by will makers suffering from extreme age, mental illness, alcoholism or other drug addiction the question of testamentary capacity arises.