Last updated 16 August 2016

A person over 18 years of age is unable to consent to medical treatment where the person has impaired decision-making capacity. Impaired decision-making capacity can be due to a wide range of things, including dementia, acquired brain injury, intellectual impairment and mental illness. It can be ongoing, intermittent or temporary.

Legislation establishes a substitute decision-making framework whereby decisions are made on behalf of an individual lacking capacity within the parameters set out in the legislation (see the Laws Relating to Individual Decision Making chapter for more information).

A person over the age of 18 years may, while they are still competent, prepare for any future incapacity and healthcare decision making under ss 35-36 of the Powers of Attorney Act 1998 (Qld) (Powers of Attorney Act) by preparing an advance health directive or appointing an enduring power of attorney authorised to make decisions in relation to the healthcare of the individual (s 32 Powers of Attorney Act).

The Supreme Court’s parens patriae jurisdiction also provides a mechanism to assist in cases involving incapacitated individuals and medical treatment. This is an inherent jurisdiction of the Supreme Court to protect the person and property of those who are unable to look after themselves, and it covers both adults lacking capacity and children. An application needs to be made to the Supreme Court, and the court has broad powers that can cover authorising treatments (e.g. blood transfusions to children against the wishes of the parents and child), reinstatement of life-sustaining treatment (see Northridge v Central Sydney Health Service (2000) 50 NSWLR 549) or authorisation of the withdrawal or withholding of medical treatment. Any decision made by the court must put the best interests of the incapacitated person or child first.

The Family Court can also withhold or grant consent to medical treatment for a child relying on its welfare jurisdiction in the Family Law Act 1975 (Cth). The Family Court’s powers are very important in cases where the parents and the child do not agree about medical treatment or a doctor is concerned about the decision made by the parents and/or the child concerning treatment (see Marion’s case (1992) 175 CLR 218; [1992] HCA 15). More recently, the Family Court has exercised its powers to permit the parents of an infant to authorise and give consent on behalf of their child to the withdrawal of medical treatment (Re Baby D (No. 2) [2011] FamCA 176 (6 March 2011)). Further information about decision making where an adult has impaired decision-making capacity is set out in the Laws Relating to Individual Decision Making chapter.