What is… Informed Consent?

Few concepts sit more squarely at the intersection of medicine and law than informed consent. It represents not only a clinical duty but also a legal and ethical cornerstone of modern healthcare.

For patients, informed consent is about autonomy and choice. For clinicians, it is about communication and responsibility. And for solicitors and expert witnesses, it is a frequent source of dispute in clinical negligence claims.

This blog explores what informed consent means, how the law has developed, and why it matters in both clinical and medico-legal contexts.

Defining Informed Consent

At its core, informed consent means that a patient has been given enough relevant information about a proposed treatment or intervention to make a voluntary, informed decision about whether to proceed.

It requires:

• Disclosure of material information: benefits, risks, alternatives, and consequences of no treatment.

• Understanding: the patient must reasonably grasp the information.

• Voluntariness: the decision must be free from coercion.

• Capacity: the patient must have the mental ability to decide.

Without these elements, consent cannot be considered valid.

The Legal Evolution: From Bolam to Montgomery

The law on informed consent in the UK has shifted dramatically over the past few decades.

The Bolam Test

Historically, consent was viewed through the Bolam test (Bolam v Friern Hospital Management Committee, 1957). Under this test, a clinician met the standard of care if their practice was supported by a responsible body of medical opinion. In practice, this often meant that disclosure of risks was judged by what doctors, not patients, thought appropriate.

The Sidaway Case

In Sidaway v Board of Governors of the Bethlem Royal Hospital (1985), the House of Lords largely reinforced the Bolam approach. Doctors were not obliged to disclose every risk, only those a reasonable body of practitioners would disclose.

The Montgomery Ruling

The landmark case Montgomery v Lanarkshire Health Board (2015) transformed this approach. Mrs Montgomery, a diabetic woman of small stature, was not warned of the increased risk of shoulder dystocia during vaginal delivery. Her child suffered severe disability.

The Supreme Court held that doctors must ensure patients are aware of any material risks involved in a treatment and of reasonable alternatives. The test of materiality is patient-centred: a risk is material if a reasonable person in the patient’s position would likely consider it significant, or if the doctor should reasonably be aware that the patient would.

This ruling shifted the focus firmly to patient autonomy.

The Practical Requirements of Informed Consent

In day-to-day practice, informed consent involves more than simply signing a form. It is a process, not a single event.

Key elements include discussion of risks and benefits in plain language, explaining alternatives, including doing nothing, checking understanding - not just telling but ensuring the patient grasps the information, and tailoring information to the patient’s circumstances, values, and priorities.

For example, a small risk of infertility may be immaterial for one patient but highly material for another who wishes to have children.

Capacity and Consent

Consent requires capacity, as defined in the Mental Capacity Act 2005. An individual has capacity if they can:

1. Understand the relevant information.

2. Retain that information long enough to make a decision.

3. Weigh the information to make a choice.

4. Communicate the decision.

If a patient lacks capacity, decisions must be made in their best interests, considering their past wishes and involving family or carers where appropriate.

When Consent is Disputed

Consent frequently features in clinical negligence claims. Common scenarios include:

• Failure to warn of significant risks that later materialise.

• Not discussing less invasive or conservative alternatives.

• Consent obtained too late, without time for reflection.

• Using generic or incomplete consent forms without discussion.

The medico-legal question becomes: would a reasonable patient in this situation have declined the procedure or chosen differently if properly informed?

The Role of Expert Witnesses

Expert witnesses are often instructed in consent-related claims. Their roles may include assessing whether the information given met the standards set by Montgomery, reviewing whether documentation and clinical notes reflect an adequate consent process and considering whether the risks not disclosed were material to the patient’s decision-making.

In practice, courts often weigh expert evidence against the claimant’s testimony. Where a patient insists they would have chosen differently, expert input on standard practice and risk disclosure is key.

Consent Beyond Surgery

Informed consent is not limited to operations. It applies to:

• Prescribing medication (side effects and interactions).

• Administering vaccinations.

• Using medical devices or implants.

• Participation in clinical trials.

• Non-invasive procedures that still carry risk.

Documentation and Record-Keeping

Courts place significant weight on documentation. If a risk discussion is not recorded, it may be assumed not to have occurred. Good practice includes making detailed notes of discussions, providing patient information leaflets and signed consent forms as supporting evidence.

Challenges in Practice

• Time pressures: Busy clinics may reduce consent to a tick-box exercise.

• Language barriers: Without interpreters, consent may not be truly informed.

• Emergencies: When immediate treatment is needed to save life, consent requirements may be modified.

• Vulnerable patients: Extra care is needed for those with learning disabilities, mental health challenges, or cultural barriers.

Final Thoughts

Informed consent is about more than legal compliance, it embodies respect for patient autonomy and shared decision-making. The law, particularly after Montgomery, places the patient’s perspective at the heart of the process.

For clinicians, this means moving beyond paternalism to true partnership. For solicitors and expert witnesses, informed consent cases require careful examination of both clinical practice and the patient’s personal circumstances.

Ultimately, informed consent is not just a formality, it is the foundation of trust in healthcare, and a recurring theme in medico-legal practice when things go wrong.