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Informed Consent And The New Law

Informed consent is a legal requirement for any medical treatment and is reinforced by professional guidelines.  Treating you without valid consent may be considered an assault or battery and can give rise to criminal or civil proceedings.

Last updated on January 18th, 2024 at 02:17 pm

Latest posts by Nikki Yavari (see all)

    Informed consent is obtained once your doctor has provided you with all appropriate information so that you can then make a fully informed choice to either accept or refuse the treatment being recommended to you. Consent is therefore a crucial component of the patient/doctor relationship, after all “patients must be able to trust doctors with their lives and health” (GMC).

    Consent issues in medical negligence usually arise in relation to surgical procedures where you believe that the doctor did not perform the surgery discussed or went on to extend the procedure beyond that which was agreed.

    What does the process involve?

    Good Surgical Practice” was published in 2002 (amended 2014) and the medical profession has since tightened up its own professional guidance withConsent: Patients and Doctors Making Decisions Together  published by the GMC in 2008.

    The guidance is mandatory and the GMC warns doctors that:

    Serious or persistent failure to follow this guidance will put your registration at risk.  You must, therefore, be prepared to explain and justify your actions”.

    The guidance reminds doctors of the principle that any decisions regarding treatment should be made in partnership with you, the patient, and that such a “partnership should be based on openness, trust and good communication”.

    The guidance advocates:

    1. No single approach to discussions about treatment or care will suit every patient, or apply in all circumstances.

    2.  Individual patients may want more or less information or involvement in making decisions depending on their circumstances or wishes. And some patients may need additional support to understand information and express their views and preferences.

    3.  Doctors must give patients the information they want or need about:

    • The diagnosis and prognosis.
    • Any uncertainties about diagnosis and prognosis, including options for further investigations.
    • Options for treating or managing the condition, including the option not to treat.
    • Benefits risks and burdens and likelihood of success for each option.
    • Any treatments they believe have greater potential benefit than those that your doctor or that hospital can offer you.

    4.  Your doctor should explore these matters with you and listen to your concerns, ask for and respect your views, and encourage you to ask questions.

    5.  Your doctor must check that you have understood, ask whether you would like more information before deciding, and explain that you can change your mind at any time.

    6.  Your doctor will share information in a way that you can understand and, whenever possible, in a place and at a time when you are best able to understand and retain it… he will allow you time to reflect, before and after you make a decision, especially if the information is complex or the treatment proposed involves significant risks…

    7.  It is your treating doctor’s responsibility to discuss this with you. If this is not practical he can delegate the responsibility to someone else, provided your doctor ensures that the person delegated:

    • Is suitably trained and qualified;
    • Has sufficient knowledge of the proposed investigation or treatment and understands the risks involved;
    • Understands, and agrees to act in accordance with, the guidance in the booklet – “Consent: Patients and Doctors Making Decisions Together”
    • Discussions with you should focus on your individual situation and the risk to you.
    • Your doctor must tell you if an investigation or a treatment might result in a serious adverse outcome even if the likelihood is very small.

    Read the full guidance on the GMC website.

    Once you have made your decision then you will be asked to sign a consent form. The form should detail the procedure that you have agreed to and list the risks of the particular procedure that were discussed with you.

    Legal Issues

    Breach of Duty

    Negligence means treatment or care that falls below medically acceptable standards – in other words, care, which at the time in question, no competent or responsible medical practitioner in the relevant field of medicine would have given.  Treatment or care which is unusual or unconventional is not negligent if there is a reputable body (although small) of medical opinion which approves it.


    It is not enough to simply prove that the care was negligent.  You also have to prove that the negligent care has caused identifiable injury and loss.  There are cases in which the patient can prove that the doctor was negligent, but that, even had the best of care been given, this would not have made any difference because, for example, there was insufficient time for appropriate care to have an effect.  There are other cases in which an entirely different cause for the injury is found which is unrelated to the negligence.

    A patient who cannot prove both that care was negligent and that the identified negligence caused the injury will not win their case.

    The standard of proof is what lawyers call the “balance of probabilities”.  Therefore a patient has to prove that it is more likely than not (that there is better than 50% chance) that the negligent care caused the injury.

    In a case relating to a failure to obtain informed consent you must prove that, had informed consent been properly obtained, then you would have chosen a different or variant procedure, or no procedure. This is often very difficult to establish given that, with the benefit of hindsight, many would say that they would not have consented if they had known of the risk.

    Case law

    The court has considered the issue of consent in a number of cases such as Bolam, Bolitho and Sidaway, and for many years the issue was decided primarily on the basis of expert medical opinion.  However, it is plain to see that there has been a clear move away from paternalism within the medical profession as highlighted from recent decisions:

    Chester –v- Afshar [2004]:

    In this case the claimant had suffered back pain for some considerable time and at times she was unable to walk or control her bladder. She was diagnosed with a disc protrusion into her spinal column and advised to have surgery. The surgery carried a 1-2% risk that even if it was performed without negligence the operation could worsen rather than improve her condition.

    Her consultant neurosurgeon Mr Afshar was under a duty to warn her of this risk although he failed to do so. The claimant had the operation which worsened her condition.

    It was the claimant’s case that if she had been warned of the risk she would not have taken the decision to have the operation straight away, but would have taken time to consider other options and discuss the risks with her family and therefore not have had the surgery on the day which she did have it. She did not say she would never have had the operation.

    “A surgeon owes a general duty to a patient to warn him or her in general terms of possible serious risks…in modern law medical paternalism no longer rules and a patient has a prima facie right to be informed of a small, but well established, risk of serious injury”.

    Lord Steyn (obiter)

    Montgomery V Lanarkshire Health Board 2015 UKSC 11

    This is such a significant case that it is worth taking the time to set out the details here.

    Nadine Montgomery gave birth to a baby boy on 1 October 1999 at Bellshill Maternity Hospital, Lanarkshire. As a result of complications during the delivery, the baby was born with severe disabilities

    Nadine Montgomery was an insulin dependent diabetic.  Diabetic women are known to have larger than normal babies with a particular concentration of weight on the shoulders and dystocia is the prime concern in diabetic pregnancies that proceed to labour.

    Mrs Montgomery was of small stature, therefore she was regarded as a high risk pregnancy and managed in the obstetric diabetic clinic.

    The risks (on the evidence) of shoulder dystocia in diabetic mothers was 9-10%, brachial plexus injury 0.2%, cerebral palsy is 0.1% and the risk of death is 0.1%.


    Mrs Montgomery was told her baby was large, and as such she was given ultrasound scans every 2 weeks, from which the foetal weight was estimated.

    It was recorded in her notes that she was worried about the baby’s size, in particular, whether it would be too big for her to deliver vaginally.

    Mrs Montgomery was so worried that Dr McLelland decided not to do her last fortnightly scan at 38 weeks in case it upset her.

    Local practice at the time was to offer elective section for estimated birth weight of 4.5 kg or over. Dr McLelland reduced that to 4 kg because of Mrs Montgomery’s size.  Going by the weight charts she estimated that birth weight would be 3.9 kg at the date mother was to be induced.

    However, Dr McLelland made the calculation on the basis of the wrong date (38 weeks rather than nearly 39 weeks) and without leaving any margin for error (USS weight estimates: allow plus/minus 10%) this meant the baby might be well over 4 kg (actual birth weight was 4.25 kg).

    Nevertheless, Mrs Montgomery

    • was not told of the risks of shoulder dystocia
    • was not offered an elective section
    • was told she would be able to deliver vaginally but, if difficulties were encountered during labour, then recourse would be had to a Caesarean section.
    Labour and delivery

    Mrs Montgomery was induced but the baby’s head would not descend.  Therefore forceps were applied and failed and the baby’s shoulder impacted.

    With half of the head outside the perineum, the judgment states:

    “Dr McLelland had never dealt with that situation before.  She described it as very stressful for Mrs Montgomery and for all the staff in theatre, including herself.  Mr Peter Stewart, an expert witness led in support of Mrs Montgomery’s case, described the situation as every obstetrician’s nightmare.  An anaesthetist gave Mrs Montgomery a general anaesthetic so as to enable the Zavanelli manoeuvre (i.e. pushing the baby back into the uterus in order to perform an emergency caesarean section) to be attempted.  Dr McLelland decided, however, that she had no other option but to try to complete the delivery…..

    She pulled the baby’s head with ‘significant traction’ to complete the delivery of the head.  In order to release the shoulders, she attempted to perform a symphysiotomy, and succeeded to some extent in cutting through the joint.  No scalpels with fixed blades were available however, and the blade she used became detached before the division of the joint had been completed.  Eventually, ‘with just a huge adrenaline surge’, Dr McLelland succeeded in pulling the baby free, and delivery was achieved…

    During the 12 minutes between the baby’s head appearing and the delivery the umbilical cord was completely or partially occluded… After his birth, he was diagnosed as suffering from dyskinetic cerebral palsy [and] a brachial plexus injury resulting in Erb’s palsy…”

    The judgement

    The trial judge (“The Lord Ordinary”) rejected Mrs Montgomery’s evidence that she had asked about the risks of vaginal delivery.  In relation to her concerns about her ability to deliver such a large baby, he found that this did not trigger any duty to explain the risks.

    For that duty to arise she would have to have “raised questions of specific risks” (paragraph 29).

    The first appeal   (The “Inner House”)

    Mrs Montgomery argued that her undisputed concerns about the baby’s size and ability to deliver were, in substance, a request for information about the risks i.e. this triggered the duty to advise.

    However Lord Eassie held:

    “Communication of general anxieties or concerns, in a manner which does not clearly call for the full and honest disclosure of factual information in reply, falls short of qualifying under Lord Bridge’s observation”.

    This was a reference to Lord Bridge in Sidaway that a “substantial risk of grave adverse consequences” ought to mean that no prudent medical practitioner could fail to warn of the risk.

    The Inner House also held that it was not the (big) risk of shoulder dystocia, it was the (tiny) risk of the grave adverse outcome that should have been the subject of warning, and that was Bolam defensible.

    The first appeal was therefore dismissed, failing on breach and on causation.

    The Supreme Court judgment 11.3.15

    The court held:

    “Shoulder dystocia is itself a major obstetric emergency, requiring procedures which may be traumatic for the mother and involving significant risks to her health.  No woman would, for example, be likely to face the possibility of a fourth degree tear, a Zavanelli manoeuvre or a symphysiotomy with equanimity.  The contrast of the risk involved in an elective caesarean section, for the mother extremely small and for the baby virtually non-existent, is stark and illustrates clearly the need for Mrs Montgomery to be advised of the possibility, because of her particular circumstances, of shoulder dystocia.”

    The Supreme Court unanimously overruled the majority decision in the House of Lords’ decision in Sidaway and held that the application of Bolam to consent was wrong:

    The new law

    An adult person of sound mind is entitled to decide which, if any, of the available forms of treatment to undergo, and her consent must be obtained before treatment interfering with her bodily integrity is undertaken.  The doctor is therefore under a duty to take reasonable care to ensure that the patient is aware of any material risks involved in any recommended treatment, and of any reasonable alternative or variant treatments.  The test of materiality is whether in the circumstances of the particular case, a reasonable person in the patient’s position would be likely to attach significance to the risk, or the doctor is or should reasonably be aware that the particular patient would be likely to attach significance to it.”(Para 87)

    Doctors must now ask themselves three questions:

    • Does the patient know about the material risks of the treatment proposed?
    • Does the patient know about reasonable alternatives to this treatment?
    • Has reasonable care been taken to ensure the patient understands this?

    The significance of Montgomery

    The law has finally caught up, as the statement from GMC chief executive Niall Dickson, explains:

    “We are pleased that the court has endorsed the approach advocated in our guidance on consent, Good Medical Practice and Consent: Patients and Doctors Making Decisions Together make it clear that doctors should provide person-centred care. They must work in partnership with their patients, listening to their views and giving them the information they want and need to make decisions.”

    Causation will of course remain difficult in such cases, but the duty to warn of risks has moved away from being a medical based decision to a patient-centred decision.

    The decision in Montgomery in relation to informed consent means that expert medical evidence as to established practice will no longer be the only factor to determine liability and so establishing a breach of duty is made easier. It may also be possible to successfully settle cases where alternative treatments are not explained or offered – especially as to do so is set out in the mandatory GMC guidance, Consent: Patients and Doctors Making Decisions Together, which is now enshrined in law.

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