Marie's nephew, François de Cossé, 11th Duke of Brissac, brought a lawsuit on behalf of her family before the Tribunal de grande instance of the Seine to try to stop the wedding. He claimed that his aunt was mentally incompetent. Marie claimed that she had thought about the marriage twelve years earlier, but had delayed on account of her grandchildren. The court determined that a nephew had no legal right to oppose the marriage of an aunt. It appointed a commission of three doctors to investigate Marie's mental state and confirmed a judicial administrator appointed on July 7 to manage Marie's estate.