Incompetence
Proving mental incompetence or "testamentary incapacity" at the time of a will's execution is one of the ways a slighted heir has to successfully challenge a will. Yet it is extremely hard to do. Although senility and dementia are common among the elderly, simply proving their existence is not enough in most courts to invalidate a will. You may wish to consult a legal adviser about the legal standards for contesting a will where you live.
