‘“Please do not give me CPR”: ‘Do Not Resuscitate’ requests in retirement living‘ is an online article written by Anita Courtney and Melanie Tan from law firm Russell Kennedy. You can read it by following the link, above.
Ambulance, Health Professional Registration, Legislation and plans, Paramedics
Australian Emergency Law 
In response to this post I received this question from a NSW paramedic:
The authors of the post that I linked to say:
They also say ‘The validity of advance directives is recognised at common law (that is, outside any legislative framework) on the basis of well-established principles of consent.’
The absence of legislation in NSW and Tasmania means that the position is governed by the common law. The common law says, to again quote Tan and Courtney ‘… means that if a competent adult refuses medical treatment it should not be given, and CPR should be withheld from a person if they are known to have made a DNR request.’
That is the position in NSW and Tasmania. If a patient declines CPR whether by signing a form, telling paramedics, having it tattooed on their chest or carrying a card that should be respected – for further discussion see the 52 posts that appear with this search https://emergencylaw.wordpress.com/?s=refusing+treatment
Where a person is acting as a substitute decision maker whether they have been appointed by a tribunal, the patient or are the ‘person responsible’ (see Guardianship Act 1987 (NSW) Part 5; Guardianship and Administration Act 1995 (Tas) Part 6) then assuming they have been properly appointed their decision to endorse a DNR order is equally binding. There may be arguments that they cannot refuse treatment on behalf of the person at the time of the emergency, so if a paramedic is in a establishment and a person says ‘I am their carer and I’m refusing treatment’ and there is no record to support then the decision may not be binding but that would also be true if they said ‘this patient has told me they don’t want to be treated’.