Johnson v Johnson

This case involved a husband's petition to the Supreme Court of New South Wales for the dissolution of his marriage on the grounds of his wife's adultery. The wife, who suffered from occasional attacks of acute mania, was represented by the Master in Lunacy, appointed as her guardian ad litem. The trial judge dismissed the petition, expressing doubt as to whether the wife possessed sufficient sanity at the time of the alleged adultery to understand her actions. The husband appealed this decision to the High Court of Australia.

The central legal issue before the High Court was whether the wife's admitted sexual intercourse with a co-respondent constituted adultery within the meaning of the Matrimonial Causes Act 1899 (N.S.W.), despite her mental condition. Specifically, the court had to determine if her insanity, to the extent it existed, rendered her incapable of forming the necessary intent or volition for the act to be considered adultery, and whether insanity could operate as a defence to such a charge. A secondary issue concerned the costs of the appeal and the hearing, particularly in relation to the guardian ad litem.

The High Court, by majority, allowed the appeal and granted a decree nisi for dissolution of the marriage. The reasoning focused on the wife's capacity to understand the nature of the sexual act, the identity of the co-respondent, and that her conduct was contrary to her marital duty. While acknowledging her mental affliction, the court found that the evidence, particularly her statements and actions at the time of discovery and her subsequent written confession, demonstrated a sufficient level of understanding and volition. The court held that her mental disease did not, in law, relieve her of responsibility for the adultery. The co-respondent was ordered to pay the petitioner's costs, and the petitioner was ordered to pay the costs of the respondent wife, including those incurred by her guardian ad litem.