The purpose of a last will and testament is to provide a will maker -- called a "testator" -- a mechanism by which he can dispose of his property in a manner he sees fit. In most instances, a testator is under no obligation to include children in his will. Thus, the legal recourse for a child left out of a will may be to contest the will.
Disinheriting
Generally, the only individuals who cannot be disinherited completely are surviving spouses, unless the married couple had an agreement, such as a prenuptial or antenuptial contract. Absent an agreement, surviving spouses cannot be entirely disinherited because the law entitles them to a portion of marital property. Children, on the other hand, may be disinherited unless the deceased parent lived in Louisiana, the only state in which a child has a right to inherit by law.
Contesting a Will
A child may assert that she was not purposely disinherited by contesting her parent's will. To contest the will, she must file a notice of contest with the probate court in the county where her parent lived. Typically, a child contesting a will must provide clear and convincing evidence that her parent's will is invalid or that she was disinherited accidentally. If the probate court is convinced, it may grant a portion of the parent's estate to the child.
Read More: Children and Contesting a Will
Grounds: Not Explicit
Although wills are generally presumed valid, there is also a presumption that a testator did not mean to disinherit a child if he didn't explicitly do so. Additionally, it may be presumed that children born after a parent's will was made may have been accidentally omitted. For example, if a parent left property to all of his children in a will then had another child after the will was executed, a probate court may conclude that the "after born" omitted child is entitled to a share.
Grounds: Undue Influence or Duress
A disinherited child may also contest a parent's will if she believes her parent was under undue influence or duress when he executed the will. If a parent was under undue influence, it typically means he was mentally or psychologically controlled or influenced by someone he trusted when making the will. Being under duress means the testator felt he had no option -- due to threats of bodily harm, coercion or physical restraint -- except to execute his will according to the instruction of the perpetrator who threatened to hurt him.