It is important to distinguish between informed consent as a doctrine and informed consent as a term used imprecisely to mean a valid consent, one where the "broad nature" (Chatterton v. Gerson ) of the treatment proposed has been explained to the patient. In the context of this essay, informed consent refers to the doctrine which underlines the amount of information that a patient should be given in relation to the risks of treatment over and above those encapsulated with the "broad nature" requirement of the inevitable and inherent risks posed by the proposed treatment.
Ethically, the issue under consideration is the right to self-determination and the mantra from all proponents of informed consent, as described in Largey v. Rotham, is that a patient cannot validly consent to the risks associated with treatment unless he has been told of them in advance. This posses a real problem for the medical staff. Whilst two patients will require a doctor to perform an operation to the same high standard, these two patients may require different information and different amounts of information relating to the risk involved, in order to enable them to decide whether to undergo the operation in the first place.
As emphasised by Lord Templeman in Sideway v. Board of Governors, whilst one patient will need all the information available to enable him/her to make his decision, another patient will find this amount of information confusing or alarming. Professional Standard and Reasonable Test The legal test applied to the standard of care afforded to a patient by his doctor has historically been the professional standard or the "bolam test" after it was described by McNair, J in the case of Bolam v. Friern Hospital Management Board .
The essential dictum from this case was that: "….. a doctor is not negligent of he acts in accordance with a practice accepted at the time as proper by a responsible body of medical opinion. " The Bolam test in relation to treatment has met with criticism and has undergone modification. Patient Standard test- An alternative test to that of the 'professional standard' is the 'patient standard' and it was the application of such a test that lead to the phrase 'informed consent' finding its way into the law reports in the American case of Salgo v.
Leland Stanford Jr . In this case the court held that a doctor owed a duty of care to the patient to disclose any facts which are necessary for the patient to form the basis of an intelligent consent to the proposed treatment. Shortly afterwards, in 1960, the American Courts held that the duty of care included disclosure of reasonable risk (Natanson v Kline ). In Canterbury v. Spence  it was held that it was for the court to determine the extent of the doctor's duty to inform of the risks of treatment.
In this case the claimant was a 19 year old man who had pain between his shoulder blades. He was referred to a neurosurgeon who told him that he would require an operation to correct a suspected ruptured intervertebal disc. The patient did not object to the operation or ask any questions, but in answer to his mother's question the doctor said that the operation was no more serious than any other operation. Following the operation the patient was rendered paralysed and was permanently disabled.
The claimant sued the doctor for failure to disclose a risk of serious disability inherent in the procedure. The court upheld the claim that the 1% risk of paralysis should have been disclosed. In doing so the court departed significantly from the professional standard test. In adopting a prudent patient test, the American courts were, arguably, making a distinction between the strictly medical aspects of clinical practice, such as making a diagnosis and the non-medical, such as communicating with patient.
English Law English law. However, manifests a reluctance to depart from the professional standard. Hatcher v. Black  was the first English case on non-disclosure of risk prior to surgical treatment. The claimant, having been assured pre-operatively that there was no risk to her voice, suffered vocal cord paralysis following surgery to correct a toxic goitre. The defendant was vindicated on the strength of the professional standard as well as causation. In directing the jury, Lord Denning said:
"None of the doctors called as witnesses have suggested that the surgeon was wrong. If they do not condemn him, why should you? " In Chatterton v. Gerson and Hill v. Potter , in both cases, the claimants sued in trespass and in negligence for non-disclosure of risks inherent in their respective surgical operations, and in each case it was held that the defendant had followed accepted medical practice. In Hill v. Potter Hirst J rejected the Claimant's argument that the doctrine of informed consent applied.