The doctrine of double effect will only protect a doctor
No. In most Australian States and Territories a doctor, nurse, carer or family member can give medication and be legally protected by the doctrine of double effect. Generally however, the medication must be ordered or supervised by a doctor or nurse practitioner.
The law in South Australia is slightly different. The medication must be given by the practitioner responsible for the person’s treatment, or a person supervised by that practitioner, such as a nurse or carer.