Crimes Act 1900 (NSW) s574B NSW
s574B notes that it is lawful for a person to use reasonably necessary force to prevent the suicide of another person.
Guardianship Act 1987 (NSW) s37 NSW
Outlines situations when a doctor may treat a patient in an emergency or, in the case of minor treatment, where there is no person responsible, where the patient is unable to consent to treatment.
Mental Health Act 2007 (NSW) NSW
Provides for non-consensual treatment for patients considered mentally ill or mentally disordered. Must be for the person’s own protection from serious physical harm or protection of others from serious physical harm.
Road Transport (Safety and Traffic management) Act 1999 (NSW) ss20(2), (3), 21 NSW
Requirement of doctors to take a blood sample from any patient admitted to hospital for examination or treatment after having been in a road accident.
Airedale National Health Service Trust v Bland  AC 789 UK
UK case that is often cited in Australian Courts. Regards a young man who has been in a persistent vegitative state with no prospect of recovery. Case concerned whether withdrawal of artificial feeding and other measures keeping Bland alive would constitute a criminal offence as the consent of the individual was not attainable. Contains discussion of principle of necessity.
In re F  2 All ER 545 (HL) UK
Case of an intellectually disabled woman in the UK. Held that the principle of necessity may be used to justify treatment for someone who may never be able to consent. Note that necessity is different from emergency. In the UK at the time there was no provision for surrogate decision making.