While an advance care directive comes into force as soon as it is witnessed in accordance with the Advance Care Directives Act 2013 (SA) [s 16(1)], it may only be used by a substitute decision maker or health practitioner if the person who gave the advance care directive has impaired decision making capacity [s 34]. Note that the impaired capacity must relate to the particular decision that has to be made at the time [s 34].
If a person who has not been appointed as a substitute decision-maker under an advance care directive acts as if they have been so appointed, then they commit an offence [s 56(2)(b)]. The maximum penalty is imprisonment for 10 years.
Impaired decision-making capacity
A person is considered to have impaired decision-making capacity in respect of a particular decision if [ss 7(1)-(2)]:
An advance care directive given by the person may set out when he or she is to be considered to have impaired decision-making capacity (however described) in relation to particular decisions [s 7(1)(b)].
Note that, under s 10, a person is presumed to have full decision-making capacity, must be allowed to make their own decisions to the extent that they are able, and may make decisions in collaboration with others.
Note further that a person may fluctuate between having impaired decision-making capacity and full decision-making capacity [s 7(2)(c)] and that a person's decision-making capacity will not be taken to be impaired merely because a decision made by the person results, or may result, in an adverse outcome for the person [s 7(2)(d)].