Breach of duty - Standard of care

Learning Outcomes

This article examines breach of duty in negligence and how the standard of care is determined and applied across different contexts. It explains the objective reasonable person benchmark and how the law calibrates the standard for skilled professionals, children, and those undertaking activities with unusual risks or constraints (such as emergencies or illness). It also sets out the structured approach courts use to assess whether the defendant’s conduct fell below the required standard, including the role of likelihood and seriousness of harm, practicality and cost of precautions, social utility, common practice, and the state of scientific or technical knowledge at the time. Finally, it covers how breach is proved in practice, including evidential inferences from res ipsa loquitur and the effect of criminal convictions in civil proceedings. On completion, you should be confident in applying these rules to single best answer questions and realistic scenarios involving professional diagnosis/treatment and risk disclosure (Bolam/Bolitho/Montgomery), the standard for learners, and the tailored standard for children.

SQE1 Syllabus

For SQE1, you are required to understand breach of duty and the standard of care in negligence, with a focus on the following syllabus points:

• the objective test for the standard of care (the 'reasonable person') and how it operates
• how the standard is adjusted for skilled professionals (Bolam) and constrained by judicial oversight (Bolitho)
• risk disclosure and the patient-based material risk test (Montgomery), including its limited exceptions
• the standard of care for children and for unskilled/learner defendants
• factors relevant to breach: likelihood of harm, seriousness of potential injury, cost/practicability of precautions, social utility, common practice, and the state of knowledge
• proving breach: evidential principles including res ipsa loquitur and the effect of criminal convictions in civil claims (Civil Evidence Act 1968, s 11)
• the court’s ability to consider social value and deterrence concerns when assessing negligence (Compensation Act 2006, and the limited role of the Social Action, Responsibility and Heroism Act 2015)

Test Your Knowledge

Attempt these questions before reading this article. If you find some difficult or cannot remember the answers, remember to look more closely at that area during your revision.

1. What is the general test used by courts to determine the standard of care in negligence?
   1. The subjective test based on the defendant's own abilities.
   2. The objective test based on the 'reasonable person'.
   3. The test based on the common practice within a specific industry.
   4. The test based on the severity of the harm caused.
2. According to the Bolam test, when is a medical professional not considered negligent in relation to diagnosis or treatment?
   1. When they act with the best intentions.
   2. When their actions are supported by any body of medical opinion.
   3. When they act in accordance with a practice accepted as proper by a responsible body of medical opinion, provided that opinion has a logical basis.
   4. When the patient consented to the risk.

3. True or False? A learner driver is expected to meet the same standard of care as a reasonably competent qualified driver.

4. Which of the following factors is LEAST likely to lower the standard of care expected of a defendant?
   1. The high cost of taking precautions against a very small risk.
   2. The defendant acting in an emergency situation.
   3. The defendant possessing a lower level of skill than average for the activity undertaken.
   4. The social utility of the defendant's actions.

Introduction

Once a duty of care is established, liability in negligence turns on whether the defendant breached that duty. Breach is assessed by reference to the standard of care the law requires in the circumstances; liability follows only if conduct falls below that standard. The standard is primarily objective and impersonal, but the law fine-tunes it in particular settings, especially for skilled professionals and children. Assessing breach is fact-sensitive: the court balances the magnitude of the risk (likelihood and potential seriousness) against the steps reasonably available to reduce or avoid that risk, the social utility of the activity, and what could reasonably be known at the time. Proof of breach is equally practical, drawing on direct evidence, logical inferences where appropriate (res ipsa loquitur), and the evidential effect of relevant criminal convictions.

Key Term: Standard of care
The level of care expected by law from a person in particular circumstances to protect others from foreseeable risks of harm. Failure to meet this standard constitutes a breach of duty.

The Standard of Care: The Reasonable Person Test

The baseline is the conduct of the hypothetical reasonable person placed in the defendant’s situation. This person is not unduly timid or reckless, but exercises ordinary prudence. The test is objective: the defendant’s personal attributes (such as inexperience, clumsiness, or poor judgment) are generally irrelevant. A defendant undertaking an activity assumes the standard applicable to that activity. Driving is a common illustration: a person who drives must meet the standard of a reasonably competent driver, regardless of their experience level.

Key Term: Reasonable Person
A hypothetical person used as a legal standard to determine whether conduct was negligent. This person exercises average care, skill, and judgment in conduct that society requires of its members for the protection of their own and of others' interests.

Two principles underpin application of the test:

• the standard tracks the activity, not the individual: the same task attracts the same standard whoever undertakes it
• the assessment is made in the circumstances as they reasonably appeared at the time, not with retrospective “perfect knowledge” after an accident

The courts repeatedly emphasise that the law guards against “reasonable probabilities, not fantastic possibilities”. Risk assessment is carried out prospectively, having regard to what could reasonably be foreseen armed with the state of knowledge at the relevant time.

Special Standards of Care

While the reasonable person test is the general rule, the standard is calibrated for certain defendants or situations.

Skilled or Professional Defendants

A person holding themselves out as possessing a particular skill or profession is judged by the standard of the reasonably competent practitioner in that field. The classic formulation appears in the medical context:

Key Term: Bolam Test
A principle stating that a professional (especially medical) is not negligent if they acted in accordance with a practice accepted as proper by a responsible body of professional opinion skilled in that particular art.

Under Bolam v Friern Hospital Management Committee, if a doctor’s diagnosis or treatment accords with a practice accepted by a responsible body of medical opinion, it is ordinarily not negligent—even if other responsible doctors would disagree. However, professional opinion must be capable of logical support. In Bolitho v City and Hackney Health Authority, the court made clear it could reject a body of professional opinion that was not internally coherent or defensible on rational grounds. Judicial oversight ensures professional standards do not immunise poor practice simply because it is widespread.

Guidance and codes (for example, clinical guidelines or practice standards) are relevant but not determinative. They inform the court’s view of what is reasonable but do not replace the Bolam/Bolitho analysis. A defendant may be able to justify a departure where there is a sound clinical reason; conversely, adherence to a guideline may still amount to negligence if, on the facts, the approach does not withstand logical scrutiny.

Risk disclosure engages a distinct standard. Montgomery v Lanarkshire Health Board reframed the duty to warn: the focus is on the patient’s right to make informed choices.

Key Term: Material risk
A risk is material if a reasonable person in the patient’s position would be likely to attach significance to it, or if the doctor knows (or ought reasonably to know) that the particular patient would be likely to attach significance to it.

Under Montgomery, doctors must take reasonable care to ensure patients are aware of material risks of recommended treatment and reasonable alternatives. This is patient-centred, not doctor-centred. There remain narrow exceptions (for example, genuine emergencies where consent cannot be obtained, or rare cases where disclosure would be seriously detrimental to the patient’s health—often termed a therapeutic exception), but these are applied sparingly.

Worked Example 1.1

Dr. Aris performs surgery on Ben using Technique A. There is a responsible body of surgical opinion supporting Technique A, although another responsible body prefers Technique B, which carries slightly fewer risks. Ben suffers a complication that is a known risk of Technique A. Is Dr. Aris likely to be in breach of duty regarding the choice of technique?

Answer:
Unlikely. Applying the Bolam test as modified by Bolitho, Dr. Aris acted in accordance with a practice accepted by a responsible body of medical opinion (supporting Technique A). Provided this opinion has a logical basis, Dr. Aris would likely not be found negligent regarding the choice of technique, even if another body of opinion favoured Technique B. The separate duty under Montgomery requires that Ben be warned of any material risks of Technique A and reasonable alternatives.

Worked Example 1.2

A diabetic patient of small stature is advised to attempt vaginal delivery. The risk of shoulder dystocia is around 9–10% in such cases. The doctor does not discuss this risk or the option of caesarean section. The child suffers hypoxic injury. Is there likely to be a breach?

Answer:
Yes. Under Montgomery, the duty is to disclose material risks and reasonable alternatives. A risk of that magnitude is material to a reasonable person in the patient’s position, and the doctor should have appreciated the patient-specific significance. Failure to warn and discuss alternatives is a breach of the Montgomery duty, even if the choice of delivery method would otherwise satisfy Bolam/Bolitho on treatment grounds.

Unskilled Defendants (Learners)

People learning a skill (e.g., learner drivers) are normally held to the same standard as reasonably competent, qualified persons performing that skill. Inexperience is not a defence. Nettleship v Weston is the leading case: the learner driver was judged against the standard of the competent driver. Public protection and the practical reality of compulsory insurance inform this approach.

This principle also applies to junior professionals. The standard is tailored to the post or task, not the individual’s experience. A junior doctor must meet the standard of a reasonably competent doctor in that role. Where out of their depth, they are expected to seek assistance rather than proceed incompetently.

Children

A child is judged by the standard of a reasonable child of the same age. The law expects less foresight and self-control from children, reflecting developmental capacity. Very young children are rarely found negligent because they lack the ability to foresee and guard against risks.

Worked Example 1.3

Two 14-year-old friends, Chloe and David, are playing with frisbees in a park. Chloe throws her frisbee carelessly, hitting David and causing a minor injury. Would Chloe be judged against the standard of a reasonable adult or a reasonable 14-year-old?

Answer:
Chloe’s conduct would be judged against the standard of a reasonable 14-year-old. The court would consider whether an ordinary, prudent 14-year-old would have foreseen the risk of injury and acted as Chloe did.

Illness and impairment

Sudden and unforeseen illness may affect breach analysis. A driver who suffers a sudden incapacitating medical episode without warning will not be in breach for continuing to drive until the episode strikes; but if early symptoms are apparent, the reasonable driver would stop or take precautions. The touchstone remains foreseeability at the time and the reasonableness of response to warning signs.

Worked Example 1.4

Sam, a driver with no known health issues, experiences a sudden and complete loss of consciousness while already driving and causes a collision. In contrast, Pat feels disorientated and “not quite right” at the start of a journey, continues driving, and has a series of minor bumps before a serious crash. Has either likely breached the standard of care?

Answer:
Sam is unlikely to be in breach if the medical episode was truly sudden and unforeseeable. Pat is more likely to be in breach: a reasonable driver would have stopped once early warning signs appeared, and persisting in driving despite them falls below the standard of care.

Assessing Breach: Relevant Factors

Once the applicable standard is identified, the court asks whether the defendant’s conduct fell below it. This is a structured balancing exercise, weighing foreseeable risks against reasonable precautions in the real-world context of the activity.

Key Term: Breach of duty
Occurs when a defendant's conduct falls below the legally required standard of care owed to the claimant.

Key factors the court considers include:

• Magnitude of the risk (likelihood and potential severity)
• Cost and practicability of precautions
• Social utility of the conduct
• Common practice
• State of knowledge at the time

These factors are interrelated; each informs what steps a reasonable person would take.

• Magnitude of the risk (likelihood and severity):

  • Likelihood: A very small risk may reasonably be ignored where precautions would be onerous or disruptive. Where the chance of harm is more than minimal, precautions are more likely to be required. Cricket ball cases contrast the point: in Bolton v Stone, balls were hit out of the ground exceedingly rarely over decades; in Miller v Jackson, balls left the ground regularly each season, so greater precautions were required.
  • Severity: Even if the likelihood is low, if the potential harm is grave, heightened precautions may be reasonable. Paris v Stepney Borough Council is the leading case: an employer owed a higher standard of care to a worker with only one good eye because the consequences of injury would be catastrophic for him.

• Cost and practicability of precautions: The court balances the risk against the burden of precautions. If precautions would substantially reduce risk at modest cost and practicality, failing to take them is more likely to be negligent. Where precautions would be disproportionately expensive or impractical given a small risk, doing nothing may be reasonable. Latimer v AEC Ltd illustrates this: closing the factory was disproportionate to the temporary, relatively small risk after flooding; reasonable steps (such as spreading sawdust) sufficed.

• Social utility of the activity: Where conduct serves an urgent or socially valuable purpose (for example, emergency rescue), the law may accept a higher level of risk. In Watt v Hertfordshire County Council, the lack of securing equipment in an urgent rescue was not negligent given the life-saving objective and short distance involved. Statute now expressly permits courts to consider whether imposing liability might discourage desirable activities (Compensation Act 2006). The Social Action, Responsibility and Heroism Act 2015 also directs courts to consider whether a person was acting for the benefit of society or demonstrating heroism in emergencies, although it has had limited practical effect.

• Common practice: Evidence of common practice may be persuasive of reasonableness but is not conclusive. A widely adopted practice can still be negligent. The court will examine whether the practice sensibly addresses foreseeable risks and is consistent with safe systems of work or accepted standards. Professional guidelines, industry codes, or statutory regulations often inform the analysis but do not automatically set the legal standard.

• State of knowledge: Conduct is judged by reference to knowledge reasonably available at the time; the law does not expect guarding against risks unknowable or scientifically undetectable then. Roe v Minister of Health illustrates this: medical procedures were judged against the knowledge in the relevant period, not later developments. Conversely, where risks are known or reasonably should be known, the standard adjusts accordingly.

Worked Example 1.5

A utility installs street works with temporary barriers. Evidence shows that blind pedestrians use the street, and managing agents are aware of this. Minimal barriers are used that a sighted person would recognise, but a blind pedestrian trips and suffers severe injury. Was breach likely?

Answer:
Likely. Given the foreseeable presence of blind pedestrians and the severity of potential harm, a reasonable utility would have adopted barriers or warnings effective for visually impaired users (for example, tactile markings or secure fencing). The magnitude and character of the risk make additional precautions reasonable, and the cost of such measures is usually modest.

Worked Example 1.6

A hospital ward’s clinical practice guideline suggests optional use of a particular device to reduce a low-frequency complication. The firm does not routinely use it; a rare complication occurs in a patient. Does adherence to the guideline end the breach enquiry?

Answer:
No. Guidelines are relevant but not determinative. The court will still ask whether, in the circumstances, failing to use the device was consistent with reasonable care. If a responsible body of opinion supports non-use and that position is logically defensible (Bolam/Bolitho), there is likely no breach. Conversely, if the responsible opinion cannot be rationally supported or if patient-specific factors make the risk more significant, the failure may be negligent.

Worked Example 1.7

A cricket club has a ground next to a residential road. Balls are occasionally hit out of the ground, roughly six times in 30 years, without causing injury. One day, a ball is hit out and injures Yasmin, who is walking past. Building a significantly higher fence would prevent this but would be very expensive. Is the club likely to be in breach of duty?

Answer:
Unlikely. Applying the principles from Bolton v Stone, the likelihood of harm occurring was very low (six times in 30 years). Balancing this small risk against the high cost of effective precautions (a much higher fence) and the social utility of playing cricket, a reasonable cricket club might justifiably disregard the risk. Therefore, the club may not have breached its duty of care.

Exam Warning

Assessing breach involves balancing competing factors. Scenarios often juxtapose a small likelihood of harm with potentially severe consequences, or modest costs of precautions with a high social utility in acting without delay. Pick out and weigh all relevant factors. Always assess knowledge at the time, and avoid judging with hindsight. In professional contexts, keep Bolam/Bolitho (for diagnosis/treatment) distinct from Montgomery (for risk disclosure).

Proving Breach of Duty

The burden of proof is on the claimant to show, on the balance of probabilities, that the defendant fell below the required standard of care. The court draws inferences from the totality of the evidence: direct testimony, documentary records, contemporary guidelines, expert opinion (in professional cases), and the plausibility of the competing narratives.

Res Ipsa Loquitur

In some cases, the circumstances of the accident themselves support an inference of negligence. Res ipsa loquitur (“the thing speaks for itself”) is an evidential tool: if appropriate conditions are met, it is open to the court to infer negligence unless the defendant provides a credible non-negligent explanation.

Res ipsa loquitur may apply if:

• the cause of the accident is unknown
• the thing causing the damage was under the defendant’s control (or management)
• the accident is of a type that would not normally occur without negligence

Key Term: Res ipsa loquitur
A legal principle ('the thing speaks for itself') allowing negligence to be inferred from the mere fact an accident happened, provided the cause was under the defendant's control and the accident was of a kind that does not usually occur without negligence.

The doctrine does not reverse the legal burden of proof; it permits an inference which the defendant may rebut by showing how the accident could have occurred without negligence. It is commonly invoked where detailed evidence is unavailable because the mechanism is obscure or the defendant has primary control of the instrumentality.

Worked Example 1.8

A supermarket customer is injured when a large display stack collapses. No-one saw the triggering event, and the stack was arranged by the store’s employees shortly beforehand. The customer alleges negligence but cannot show the precise cause. Does res ipsa loquitur assist?

Answer:
Potentially. The display was under the store’s control and, ordinarily, properly arranged displays do not collapse. If the store cannot provide a credible non-negligent explanation (for example, a sudden unforeseeable external event), the court may infer negligence from the circumstances.

Criminal Convictions

Under the Civil Evidence Act 1968, s 11, a criminal conviction for an offence arising from the same incident is admissible as evidence that the defendant committed the offence. In negligence claims, relevant convictions provide prima facie evidence that the conduct occurred (for example, careless or dangerous driving), supporting breach. The defendant may still attempt to disprove negligence in the civil claim, but the conviction is powerful evidence that the standard of care was not met.

Convictions for offences that do not involve carelessness (for example, administrative offences unrelated to driving standards) may have little or no bearing on breach. Always examine whether the conviction directly relates to the negligent conduct alleged.

Key Point Checklist

This article has covered the following key knowledge points:

• Breach of duty is assessed by reference to an objective, impersonal standard of care judged prospectively, not by hindsight.
• The general standard is the reasonable person undertaking the activity in question; inexperience does not lower the standard.
• Skilled or professional defendants are judged by the reasonably competent practitioner in that field; Bolam governs diagnosis/treatment with judicial oversight under Bolitho.
• Risk disclosure engages a distinct, patient-centred duty: under Montgomery doctors must warn of material risks and reasonable alternatives, subject to narrow exceptions.
• Children are judged by the standard of a reasonable child of the same age; very young children are rarely negligent.
• Illness and sudden impairment cases turn on foreseeability and the reasonableness of response to warning signs.
• Breach analysis balances the magnitude of risk (likelihood and seriousness) against the cost and practicability of precautions and the social utility of the defendant’s conduct.
• Common practice and guidelines are relevant but not conclusive; the court may find a common practice negligent if it fails to address obvious risks.
• Conduct is judged by the state of knowledge at the time, not by subsequent advances or hindsight.
• The claimant bears the burden of proving breach; res ipsa loquitur may permit an inference of negligence in appropriate circumstances.
• A relevant criminal conviction is admissible as evidence supporting breach under the Civil Evidence Act 1968, s 11.
• Statute permits courts to consider whether imposing liability would discourage desirable activities (Compensation Act 2006); SARAH 2015 has a limited role.

Key Terms and Concepts

• Standard of care
• Reasonable Person
• Bolam Test
• Material risk
• Breach of duty
• Res ipsa loquitur

Worked Example 1.9

During an urgent response, a fire engine travels through a red light at speed with sirens active. A collision occurs in the junction. Is the driver automatically shielded from breach given the emergency?

Answer:
No. Social utility is relevant but does not automatically absolve negligence. The court will weigh the urgency and life-saving purpose against the foreseeability of harm and the steps reasonably available to reduce risk (e.g., slowing sufficiently to check the junction was clear). If proceeding at speed through a blind red-light junction was unreasonable, breach may be found notwithstanding the emergency.

Worked Example 1.10

A junior doctor prescribes a standard dose of a medication without checking a patient’s record that shows a known allergy. The ward is busy, and the doctor is new. The patient suffers an allergic reaction. Is inexperience a defence?

Answer:
No. The standard is tailored to the post, not the individual. A reasonably competent doctor in that role would consult the record to avoid known allergies. Busyness or inexperience does not lower the standard; where uncertain, the junior doctor should seek assistance. Failure to check or to ask falls below the standard of care.