Will contests generally focus on the assertion that the testator lacked testamentary capacity, was operating under an insane delusion, or was subject to undue influence or fraud.
Many states consider such clauses void as a matter of public policy or valid only if a will is contested without probable cause.
[3] Most other legal traditions enforce some type of forced heirship, requiring that a testator leave at least some assets to their family, particularly the spouse and children.
Under such facts: Common grounds or reasons for contesting a will include lack of testamentary capacity, undue influence, insane delusion, fraud, duress, technical flaws and forgery.
Undue influence typically involves the accusation that a trusted friend, relative, or caregiver actively procured a new will that reflects that person's own desires rather than those of the testator.
Such allegations are often closely linked to lack of mental capacity: someone of sound mind is unlikely to be swayed by undue influence, pressure, manipulation, etc.
However, that is dependent on the circumstances of such a relationship and typically the burden is initially on the person contesting to show undue influence.
[15] Insane delusion is another form of incapacity in which someone executes a will while strongly holding a "fixed false belief without hypothesis, having no foundation in reality.
The caretaker asserted that the decedent was suffering from an insane delusion at the time the will was executed and that she thus lacked testamentary capacity.
Duress involves some threat of physical harm or coercion upon the testator by the perpetrator that caused the execution of the will.
A will contest may be based upon alleged failure to adhere to the legal formalities required in a particular jurisdiction.
Forgery can range from the fabrication of an entire document, including the signatures, to the insertion or modification of pages in an otherwise legitimate will.
They often originate with an adult child who, feeling short-changed in a parent's will, accuses a sibling of doctoring the document".
In the United Kingdom, wills are often contested on the basis that a child of the deceased (or somebody treated as such) was bequeathed nothing or less than could reasonably be expected.
In some cases, the threat of a will contest is intended to both pressure the estate into avoiding the expense of a trial and forcing an out-of-court settlement more favorable to disgruntled heirs.
[3] However, those who make frivolous or groundless objections to a will may be forced to pay the costs for both sides in the court battle.