Recent cases concerned with the future medical treatment of a child with a life-limiting condition have presented, on appeal, the argument that the threshold for intervention in a parental decision about the child’s medical treatment should be significant harm rather than best interests. The basis of the claim is that parents know their child best and, consequently, should have the right or authority to make decisions about their child’s future. Although unsuccessful before the courts, these legal arguments have inspired the inclusion of provisions in Bills before Parliament aimed at enhancing parental authority in such cases. This article examines this modern reincarnation of the claim to parental authority, in the context of the medical treatment of a seriously ill child. It argues that reform of the law to re-assert parental authority would be a seriously retrograde development—a contemporary conservative reformulation of the child as object—which would significantly erode the rights of the child. Rather, it is argued that the child should be at the centre of the shared care of parents and professionals focused upon the individual child’s needs, interests and rights. This article concludes with a fictional account of an attempt to reform the law to place the interests, rights and voice of the child at the centre of determination of their future medical treatment. Keywords: children’s interests, rights and voice; parental authority; children’s medical treatment; best interests or significant harm threshold.