Joan was implicated in Margaret's adultery case during 1314; Margaret was accused and convicted of adultery with two knights, upon the testimony of their sister-in-law, Isabella. Joan was suspected of having secretly known about the adultery; placed under house arrest at Dourdan as punishment, it was then implied that Joan was guilty of adultery herself. With Philip's support she continued to protest her innocence, and by 1315 her name had been cleared by the Paris Parlement, partially through Philip's influence, and she was allowed to return to court. It is unclear why Philip stood by her in the way that he did. One theory has been that he was concerned that if he were to abandon Joan, he might also lose Burgundy; another theory suggests that his slightly "formulaic" love letters to his wife should be taken at face value, and that he was in fact very deeply in love.