People aged 16 years and over can consent to their own medical treatment [Consent to Medical Treatment and Palliative Care Act 1995 (SA) s 6].

An exception to this is when a person's decision-making capacity is impaired. A person will be taken to have impaired decision-making capacity in respect of a particular decision if they are not capable of understanding, retaining or using information relevant to the decision or communicating their decision (including by reason of being comatose or otherwise unconscious) [s 4(2)].

A person will not be taken to be incapable of:

a person may fluctuate between having impaired decision-making capacity and full decision making capacity [s 4(3)].

The other exception is in emergency situations, to which separate rules apply, see Emergency medical or dental treatment.

Who may consent and in what order?

Where a person has impaired decision making capacity and is unable to consent to treatment, health practitioners may be guided by an advance care directive made and/or substitute decision maker appointed under the Advance Directives Act 2013 (SA), see Consent to Medical Treatment and Palliative Care Act 1995 (SA) s 14A and Advance Care Directives.

If the person has not made an advance care directive and/or appointed a substitute decision maker, a "person responsible" for the person can give consent [s14B]. A "person responsible" for the person includes a "guardian" (see below), a "prescribed relative" (see below), an "adult friend" (see below) or an "adult who is charged with overseeing the ongoing day-to-day supervision, care and well-being" of the person (see below)

If you are not actually a person responsible for the person according to the definitions set out below, then it is an offence to represent to a medical practitioner that you are or give consent [s 14D]. The maximum penalty is 2 years imprisonment.

If a guardian has been appointed by the Guardianship Board (prior to 30 March 2015) or SACAT (on or after 30 March 2015), the guardian is the person responsible for the patient and can consent. See GUARDIANSHIP AND ADMINISTRATION.

If no guardian has been appointed, then a prescribed relative of the patient who has a close and continuing relationship with the patient can consent.

A prescribed relative is defined as any of the following:

There is no order of priority among relatives. However note that in relation to organ and tissue donation, there is an order of priority among relatives, see Organ Donation.

If there is no prescribed relative available or willing to act, then an adult friend of the patient who has a close and continuing relationship with the patient can consent.

If there is no prescribed relative or adult friend available or willing to act, then an adult who is charged with overseeing the ongoing day-to-day supervision, care and well-being of the patient (for example, the Director of Nursing in aged care) can consent.

As a last resort, SACAT can consent. However, SACAT will not do so of its own initiative; it will only consider doing so on the application of a person with a proper interest in the matter, such as a medical practitioner.

Some types of treatment, such as termination of pregnancy, sterilisation and prescribed psychiatric treatment, can only be approved by SACAT [s 14A(3)].

How can I specify who may consent to what?

While still mentally competent, a person over the age of 18 years may prepare for the possibility that they may have impaired decision-making capacity in the future by making an advance care directive, see ADVANCE DIRECTIVES - Making an advance care directive.

A person responsible for providing consent on your behalf needs, as far as is reasonably practicable, to make a decision that reflects the decision that you would have made in the circumstances had your decision-making capacity not been impaired [s 14C]. If a person has given an advance care directive under which no substitute decision-maker has been appointed, but the patient's wishes or instructions in relation to treatment are recorded, it may be necessary to give effect to those wishes or instructions.