General principles: treatment
Consent and battery
In general, medical treatment may only be given lawfully to a patient with that patient's consent. A doctor who acts without a patient's consent risks criminal prosecution for assault or, more likely, being sued for damages in the tort of battery. A signed consent form is only evidence (not conclusive) that a patient has given consent to a treatment. It is the reality of the patient's consent which is the concern of the law (Chatterton v. Gerson ).
Exceptionally, medical treatment may be given without consent where the patient is unable to consent, for example, where the patient is unconscious in an emergency or where the patient is permanently unable to consent through mental disability and the treatment is reasonably necessary in that patient's best medical interests (Re F (A Mental Patient: Sterilisation) ).
A valid consent in law requires three elements:
(i) the patient must be competent to consent;
(ii) the consent must be based upon adequate information;
(iii) the consent must be voluntarily given.
Competence to consent
A patient will be competent to give consent if he or she is capable of understanding what is involved in the medical treatment, including the procedure itself, its consequences and the consequences of non-treatment.
An adult patient (i.e. has attained the age of 18) will usually be presumed to be competent to understand a medical procedure unless there is good reason to doubt it, for example, if he or she is mentally ill, mentally disabled or affected by external factors such as drugs, alcohol, extreme pain, panic or shock.