It is increasingly recognised that persons with mental illness experience physical health issues at greater rates than the general population and that there are significant barriers to accessing appropriate treatment. One less obvious barrier to appropriate care may be the law. This review examines the legal regimes within Australia and New Zealand that regulate consent for medical and surgical treatment for persons detained under mental health legislation. The review begins with a brief overview of concepts of consent and capacity then examines the law with regards to consent for non-psychiatric treatment for persons detained in psychiatric facilities. The complexity and cross-jurisdictional consistency is considered and potential future directions and possibilities for reform are discussed.