Divorce statutes in most states consider several defenses in case of fault-based divorce, such as recrimination, condonation, reconciliation, collusion, and connivance. States traditionally have allowed mental illness as a common law affirmative defense in fault-based divorce actions, particularly against charges of adultery, cruelty, and desertion. Under a typical scenario, the defendant was required to plead the defense and prove that mental illness prevented the defendant from recognizing that the offending act was wrong. In states that allow fault-based divorce and that have detailed statutory schemes governing divorce actions, the general movement has been to limit or eliminate common law divorce defenses such as mental illness.
Mental illness can be defined as a person’s inability to manage his or her own personal affairs, health, property, or day-to-day activities or the inability to express personal opinions, desires, wishes, feelings, and intentions due to brain damage or mental incapacity, mental disorder, imperfect or delayed brain development, or impairment or deterioration of the brain.
Mental incapacity is the basic inability to understand the consequences of conduct of the afflicted person and of others. The main way to prove a spouse’s mental incapacity is by adjudication of mental incapacity by an appropriate authority. This usually involves expert testimony by a psychologist or psychiatrist. Confinement to a mental health or rehabilitation institution also can be persuasive evidence of mental illness or incapacity.
To use mental illness as a defense to a fault-based divorce action, the afflicted party generally must prove that he or she was not able to understand and recognize that the offending act was legally wrong. When considering mental illness as a defense to fault-based divorce, courts examine the severity and the degree of mental illness and whether the mental incapacity is responsible for the alleged divorce grounds. If the party is found to be able to understand the consequences of his or her conduct, then mental illness usually fails as a defense. Generally, the mental impairment should of the same severity and degree as those used in the criminal law context.