Consent is a fundamental principle of medical treatment. Every patient has the right to make informed decisions about their own body, and healthcare professionals have a legal duty to ensure that consent is properly obtained. Failures around consent can give rise to medical negligence claims, usually where a patient was not properly informed of the risks involved in a surgical procedure. This article discusses how consent is assessed in medical negligence claims and when a failure to obtain informed consent may give rise to a claim for compensation
What Is Valid Consent?
For consent to be legally valid, it must be:
- Given voluntarily – i.e. freely and without pressure or coercion.
- Given by a patient with capacity – meaning they can understand, retain, and weigh the relevant information.
- Informed – the patient must be given sufficient information about the treatment, alternatives, and risks.
What is Informed Consent?
What constitutes informed consent can be contentious. A patient should be told, in a way that they can understand, the potential risks and benefits of treatment and what the alternative treatment options are, but it doesn’t necessarily mean that a doctor has to explain everything about the proposed treatment.
Historically, a doctor’s duty to warn patients of risks was a reasonable doctor standard and a matter of expert medical opinion. The landmark Supreme Court case of Montgomery v Lanarkshire Health Board (2015) reshaped informed consent law in the UK making it a reasonable patient focused standard. The law now requires that doctors have a duty to take reasonable care to ensure patients are aware of:
- Any material risks involved in the recommended treatment
- Reasonable alternative treatments, including the option of no treatment at all.
To judge whether a risk is material and informed consent has been obtained a court will ask itself whether:
- A reasonable person in the patient’s position would attach significance to it or
- The doctor knows (or should know) that the patient would consider it significant
In other words when seeking consent to treatment the question of whether the information given to a patient is adequate is judged from the perspective of the reasonable person in the patient’s position not the doctor ‘s perspective.
Common Breaches of Informed Consent
A failure to obtain informed consent is a Breach of Duty
Consent-related failures can arise in many ways, including:
- Failure to explain known risks or side effects of surgery
- Inadequate discussion of alternative treatment options
- Using overly technical language a patient cannot understand
- Rushing the consent process or obtaining consent immediately before surgery
- Proceeding with a different procedure from the one agreed
- Not recognising language or cultural barriers
Even if a procedure was performed competently, a failure to obtain proper informed consent may still give rise to a claim.
What if the Patient Signed a Consent Form?
Whilst signing a consent form is a crucial part of a doctor obtaining informed consent,signing a completed form is not the same as informed consent. Informed consent is a process which requires meaningful discussion between clinician and patient which should be tailored to the individuals’ circumstances, concerns and priorities so written consent forms alone are not enough if the underlying discussion behind them was inadequate.
Causation: Would the Patient Have Decided Differently?
In consent-based negligence claims, it is not enough to show that some information provided to the patient was missing or that other treatment options were available. A claimant must also establish on a balance of probabilities that:
- Had informed consent been properly obtained, they would have made a different decision and chosen a different treatment /procedure or no treatment at all ( this is known as factual causation) and
- The injury or harm suffered would have been avoided as a result (known as medical causation)
Establishing factual causation in consent cases is often very difficult as in the knowledge of a poor outcome most of us would say, with the benefit of hindsight, that we would have made a different choice. Proving causation involves very detailed witness evidence about a patient’s mindset, priorities, and decision-making at the time. The statement needs to explain what they would have done and why, had they had they been fully informed about the treatment.
What are the Exceptions to the Duty to obtain Informed Consent?
There are, of course, some exceptions to the rule.
- Emergency situations, where treatment is necessary to save a life or prevent serious harm, where the patient cannot consent
- Therapeutic exceptions, where disclosure of such risks would in the reasonable exercise of medical opinion cause serious harm to the patient’s health
Case Examples: How do the Courts Approach Consent?
The courts have considered consent issues in a number of important medical negligence cases. These examples illustrate how the failure to provide adequate information can lead to successful claims, even where the treatment itself was carried out competently. As well as showing how difficult it can be to demonstrate that a different choice would have been made and how the law on informed consent focuses on material risks and not every surgical permutation.
Montgomery v Lanarkshire Health Board (2015)
As mentioned above this landmark Supreme Court decision reshaped the law on consent establishing that, rather than being a matter for clinical judgment to be assessed by professional medical opinion, a patient should be told what they want to know, not what the doctor thinks they should be told.
Mrs Montgomery, a woman with diabetes and of small stature, gave birth to a baby boy in October 1999.Unfortunately because of complications during delivery he was born with severe disabilities. Her obstetrician had not disclosed the 9-10% risk of the baby’s head becoming stuck behind the maternal pubic bone during vaginal birth (known as shoulder dystocia) despite Mrs Montgomery asking if her size was a potential problem. Mrs Montgomery sued for negligence, arguing that, if she had known of the increased risk of this complication, she would have requested a caesarean section. The Supreme Court found that the failure to warn of this risk and the available alternative of a caesarean amounted to breach of duty and that she would have chosen a caesarean had she been properly informed.
Thefaut v Johnston (2017)
Ms Thefaut had spinal surgery and suffered nerve damage leaving her with severe back and leg pain. She alleged that she had not been adequately warned about the risks, giving evidence that the comforting and optimistic advice she received failed to give her full and accurate advice about the risks and benefits of surgery .The Defendant had given advice to the Claimant 3 times before surgery , in a short telephone conversation, a follow up letter and finally during a brief conversation before the operation .The court criticised the over estimation of the prospects of success ( advised as at least 90% when the agreed evidence was the chances had been 85% ) and the underestimation of the risks ( the consultant had advised the risks were very small whereas the experts agreed that the risk of deterioration was around 5 %) Finally the court criticised the lack of adequate time and space given to the doctor patient dialogue finding that a 4-5 minute telephone conversation a fortnight between surgery and a conversation immediately before surgery were not sufficient to remedy any shortfalls in the advice on the written letter and defects in the consent process . This is a very important decision reinforcing the legal shift towards a high threshold for patient consent and need for a personalised approach when obtaining this.
Diamond V Royal Devon & Exeter NHS Trust (2019)
The Claimant in this case alleged that she had not been properly informed before undergoing mesh-based hernia repair of the alternative for suture repair of her hernia. The consultant did not ask if she intended to get pregnant in the future -which was of relevance because of the adverse risks for pregnancy following mesh based repair .The consultant didn’t advise as to the suitability of suture repair.The Court ultimately found that whilst the surgeon had breached his duty to obtain informed consent this breach had caused no damage as the Claimant would have opted for the procedure even if she had had all of the relevant information. The Claimant had given evidence at trial that she would have chosen suture repair but the trial judge found that to opt for suture repair would have been irrational and that the Claimant was not a person who would act irrationally. This case illustrates the difficulties for Claimant’s in making claims for consent, the Claimant was able to establish that informed consent was not given and that her doctor had breached his duty in this respect, but the Claim still failed as causation was not established.
Negus & Guys and St Thomas’ NHS Foundation Trust (2021)
The Claimant underwent aortic valve replacement surgery during which a small mechanical valve was implanted. She later required revision surgery during which complications occurred and the Claimant subsequently died of heart failure. The High Court had to consider whether the surgeon had failed to obtain informed consent by not explaining highly technical alternative surgical options. Applying the Montogomery standard, the Court ruled there was no breach of duty for failing to explain technical choices that were unlikely to be understood by an ordinary patient. This case underlines that the doctor’s duty is to advise on what a reasonable patient would regard as material.
Tosh V Gupta (2025 )
In this recent Judgment the Claimant alleged a failure to explain the risks of anal stenosis – a rare but serious complication, and alternative treatment options, before a routine surgical procedure for haemorrhoids. She alleged that had those risks been explained she would have declined or deferred treatment. The Defendant clinician relied on the standard consent documentation that did detail the risk of anal stenosis and the fact that a leaflet had been provided detailing the alternatives to treatment. However, the Claimant alleged that the risks and options had not been discussed verbally. The Court ultimately accepted the Defendant’s evidence finding that the discussions at their meeting taken together with the leaflet about alternative options were sufficient to discharge his duty to obtain informed consent. In rejecting the Claimant’s evidence, the judge commented that the Claimant’s evidence was particularly affected by the application of hindsight highlighting the importance of factual witness evidence in this type of case .Whilst the Claimant in this case was unsuccessful the case does serve to demonstrate the courts willingness to examine closely the quality of the consent dialogue
Recent Case on Consent settled by Moosa-Duke Solicitors
MDS has recently settled a complex spinal injury claim arising from a failure to obtain informed consent. The case shows how harm can arise not only from what clinicians do but from what they fail to fully explain.
Of course, each case relating to a failure to obtain informed consent will turn on its own facts, which is why specialist legal advice is essential when consent issues arise.
Why Consent Issues Matter. How Can We Help You?
Sarah Grogan , Legal Director and Specialist Medical Negligence Solicitor from MDS, said
“As a firm we see time and time again that medical negligence claims are not necessarily about poor treatment but about poor communication. Many clients tell us that they would have made a different decision had they been properly informed. That is why the principles set out in Montgomery remain so important for patient safety”
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