The Californian Supreme Court has found that people who engage in high-risk sex should inform their partners that they may carry HIV, even if they have not been tested as HIV positive.

Yesterday, in a majority ruling, the court found that a man who was accused of passing on HIV to his ex-wife on their honeymoon had “constructive knowledge” of his past gay sexual behaviour that should have led him to warn her of the dangers of having sexual intercourse with him.

Justice Marvin Baxter delivering the judgement said: “Society has an overriding policy of preventing the spread of sexually transmitted diseases, especially HIV, which would be enhanced by imposing a duty of care on those who have reason to know they are infected with HIV.”

The couple were identified only as Bridget B and John B. Mr Mrs B last had sexual intercourse on their wedding night. Mr B claimed at the time that he was disease free and thus insisted on unprotected sex.

Mr B later told Mrs B that he had been engaging in sexual intercourse with other men. In the proceedings that followed, Mrs B demanded to know the names and addresses of all of her former husband’s gay partners.

Two of the Judges disagreed with the decision, one claiming that it was unfair to punish someone who didn’t know that he had HIV, the other warned of the potential for “vengeance” cases from ex-lovers.