At the time an individual signs his will, he must have the mental capacity to understand the nature of his action. When the individual does not have the requisite capacity, the will may be successfully challenged. Though each state defines legal capacity slightly differently, the main factors generally include the individual's ability to understand the meaning of the will, the property he is giving away and the beneficiaries to whom he is giving his property. The mental state at the moment the individual signed the will is all that is relevant; his mental capacity before signing, after signing and at death are all irrelevant. It is possible for an individual to be only temporarily incapacitated. For a successful will contest, the challenger has the burden to prove incapacity at the time the will was signed.
Each state has its own requirements as to how a will must be drafted to be legal. Failing to meet even a single required formality is enough to provide grounds for a will challenge. For instance, while some states allow holographic wills -- documents that are in the deceased's own handwriting and signed at the bottom -- many require that witnesses sign the document before the will is valid. If the will has no witnesses, it may be successfully challenged. Some states require that the witnesses be disinterested parties, which means they are not beneficiaries under the will. All states require that the will be drafted when the individual is at least 18 years old, though many provide exceptions in the event that the individual is in the armed forces or married.
Fraud or Undue Influence
A will must be an accurate portrayal of the deceased's true wishes. If another individual has influenced her decisions during the will-making process, you may be able to challenge the will. Not all outside influence will invalidate the document, however. To support a valid challenge, the influence must come from a person in a position of trust who has benefited in the will from his influence. For instance, a caregiver who withholds medication from the individual until she signs a will giving all her property to the caregiver would be committing undue influence. Fraud, in which the deceased was deceived in some way into signing a will or including provisions in her will that she did not intend, is also sufficient to uphold a will contest.
An individual may revoke his will in a variety of ways. A new will is generally assumed to supersede an older will, and a successful will contest may be based upon the existence of a new will. An individual may also expressly revoke his will by drafting a new document expressing that he no longer wishes his will to be valid. Divorce or marriage may also invalidate a will, as probate courts are reluctant to rely on a document that was drafted when the deceased was in a very different familial situation.