An integral part of the doctor and patient relationship is the notion of consent which is wrapped up with the concept of autonomy. Medical procedures typically involve trauma to the body that would invoke criminal sanctions were they not performed by medical practitioners. Except in emergency situations a medical practitioner must obtain a patient’s consent prior to carrying out a procedure. This is because a person has the right to decide what happens to their body.
For example, if an adult with full legal capacity decided that they do not want to have a particular medical treatment, even where that treatment would save their life and they will die if they do not have it, the medical practitioner cannot force the person to have the treatment.
This is also the case with Advance Care Directives – a person can use an Advance Care Directive to dictate in advance what treatments they will or will not consent to. To administer treatment to a patient without their consent is an assault, in civil law this is known as trespass to person or an intentional tort.
There are cases where the consent of a person to a medical procedure is vitiated (removal of legal validity) due to the actions of the medical practitioner. The famous case of Dean v Phung  NSWCA 223, honed in on that particular issue. In that case a patient received a large amount of invasive and unnecessary dental work. The patient had consented to the treatment but that was because the dentist had informed him that he had needed the treatment. Mr Dean had not needed the treatment and therefore the provision of the treatment had been an assault. The fact that Mr Dean had consented did not matter as the treatment he had received was not treatment that was necessary or capable of treating his actual dental condition.
An action for trespass to person can bring significant advantages in the damages that are recoverable. Firstly, trespass to person claims are not covered by the Civil Liability Act (2002) NSW, which means that the statutory caps on damages do not apply to these kinds of cases. Secondly the court can demonstrate its disapproval of a particular conduct by awarding punitive or exemplary damages designed to punish and deter.
There are difficulties in suing for an assault or a trespass to person claim due to the fact that most insurance policies specifically exclude indemnity for intentional acts. This means that even though a patient may be able to successfully sue their medical practitioner they may not be able to recover any damages unless the medical practitioner has assets that can be used to pay the claim. There are exceptions to this rule in some circumstances where the medical practitioner was an employee of an organisation and or government body.