Someone seeking a marriage annulment in California is hoping to have the court system legally state that the marriage never occurred because it was totally illegal. This is done by a court process that looks at the marriage in terms of its validity when it occurred. A spouse or couple must have specific "grounds" for requesting the annulment, and it is the grounds that demonstrate how the marriage was formed under illegal circumstances. Marriage annulment in California can be granted when one of the parties suffered duress, mental illness, was unknowingly entered into the arrangement, or if one is impotent, underage, a bigamist, or related by blood. It is up to the parties seeking the annulment to demonstrate evidence proving that the grounds they are claiming are valid.