Breach of duty - Current state of knowledge

Learning Outcomes

This article explains the assessment and proof of breach of duty in negligence, including:

• Assessment of breach by reference to an objective standard, measuring conduct against what a reasonable person would have done in the circumstances
• The main factors influencing the standard of care: likelihood and seriousness of harm, cost and practicality of precautions, social utility, and common practice
• Special standards for skilled defendants (Bolam and Bolitho; Montgomery on disclosure of risk), learners and unskilled defendants, and children
• How emergencies, illness, and unexpected incapacity bear on breach
• The relevance of information reasonably available at the time and why hindsight is impermissible; assessing the “state of knowledge” factor
• Evidential tools for proving breach, particularly res ipsa loquitur and section 11 of the Civil Evidence Act 1968, including their effect on evidential burdens

SQE1 Syllabus

For SQE1, you are required to understand how breach of duty is determined in negligence claims, with a focus on the following syllabus points:

• the objective standard of care and the 'reasonable person' test
• factors affecting the standard of care (likelihood and seriousness of harm, cost and practicality of precautions, social value of conduct)
• special standards for professionals, children, and unskilled defendants
• the relevance of knowledge available at the time of the alleged breach
• methods for proving breach, including res ipsa loquitur and relevant criminal convictions
• the role and weight of common practice, professional guidelines and industry standards in setting and evidencing the standard of care
• the effect of emergencies and illness on breach (including unexpected incapacity)
• the evidential impact of a criminal conviction under the Civil Evidence Act 1968 (s 11)

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 main test used by courts to determine if a defendant has breached their duty of care in negligence?
   1. The defendant’s personal intentions
   2. The standard of the reasonable person
   3. The standard set by the claimant
   4. The strict liability test

2. True or false? A newly qualified doctor is judged by the standard of a competent doctor in that post, not by their own inexperience.

3. Which of the following factors may increase the standard of care required?
   1. The risk of harm is very unlikely
   2. The potential harm is very serious
   3. The cost of precautions is extremely high
   4. The defendant’s actions have high social value
4. In which situation might the doctrine of res ipsa loquitur assist a claimant?
   1. A car accident with multiple eyewitnesses
   2. A patient suffers injury during surgery, but the cause is unknown and under the hospital’s control
   3. A slip on a wet floor with clear warning signs
   4. A defendant admits to careless driving

Introduction

Once a duty of care has been established, the next step in a negligence claim is to show that the defendant breached that duty. Breach of duty occurs when the defendant’s conduct falls below the standard required by law in the circumstances. This standard is usually assessed objectively, by reference to the actions of a hypothetical “reasonable person.” The court will consider all the circumstances to decide if the defendant’s behaviour was sufficiently careful. The claimant bears the burden of proving breach on the balance of probabilities.

Key Term: breach of duty
Breach of duty is when a defendant’s conduct falls below the standard of care required by law, exposing others to a foreseeable risk of harm.

The Objective Standard: The Reasonable Person

The objective test compares the defendant’s conduct with that of the reasonable person—someone of ordinary prudence, neither over-cautious nor reckless. The law asks not what this defendant thought or intended, but what risks a reasonable person in the same situation would have foreseen and guarded against by taking reasonable precautions. Personal idiosyncrasies and inexperience do not reduce the standard: the law sets a single, objective benchmark to ensure consistent protection.

Key Term: standard of care
The level of caution or competence expected from a reasonable person in the defendant’s position, taking into account all the circumstances.

A breach analysis is a balancing exercise. The court weighs the magnitude of the risk against the steps available to mitigate it and their cost and practicality. It is not a retrospective perfection test: the question is what the reasonable person would have done at the time, with the information then reasonably available, not what later emerged with hindsight.

Factors Affecting the Standard of Care

The court will weigh several factors to decide what the reasonable person would have done:

• Likelihood of harm: The more likely harm is, the more care is required.
• Seriousness of harm: If the potential harm is grave, a higher standard is expected, even if the risk is small.
• Cost and practicality of precautions: If precautions are easy and cheap, failure to take them is more likely to be negligent. If precautions are very costly or impractical, not taking them may be reasonable.
• Social value of conduct: If the defendant’s actions have high social value (e.g., emergency rescue), the standard may be slightly relaxed, but not abandoned.
• Common practice: Following common practice in a trade or profession is evidence of reasonable care, but not conclusive.

These factors do not operate as rigid rules. They are guides to an overall assessment of what reasonable prudence required. For example, a very low probability of harm (such as a cricket ball leaving a well-fenced ground) may justify modest precautions, but where the potential injuries would be catastrophic (such as a loss of sight), more onerous measures may be expected even if the risk materialises rarely. The practicalities and costs of additional precautions matter, but they cannot trump a serious and obvious risk if proportionate steps were available.

Social utility is a permissive rather than determinative factor. The Compensation Act 2006 confirms that courts may consider whether imposing particular precautions would deter desirable activities; similarly, the Social Action, Responsibility and Heroism Act 2015 signals that responsible interventions in emergencies are relevant context. Neither statute alters the fundamental test: the defendant must still act with reasonable care in the circumstances.

As to common practice, evidence that others do (or do not) take a precaution is relevant, but not decisive. If a practice is itself careless, adherence to it will not save a defendant; neglect of duty does not become reasonable by repetition.

Worked Example 1.1

A supermarket’s floor becomes slippery after a sudden rainstorm. Staff put up warning signs and mop the area, but a customer slips in a spot not yet cleaned.

Question: Has the supermarket breached its duty of care?

Answer:
Probably not. The supermarket took reasonable steps to warn and clean. Closing the store would be disproportionate. The standard is reasonable care, not absolute safety.

To make this assessment, the court would consider the likelihood of accidents in rapidly changing conditions, the seriousness of potential injury, the low cost and practicality of visible warning signs and prompt mopping, and the absence of feasible further measures without shutting the store.

Special Standards of Care

The reasonable person test is modified in certain situations to reflect the defendant’s role or attributes. The modification remains objective: it asks what a reasonable person with the relevant skill or age would have done.

Professionals and Skilled Defendants

A professional (such as a doctor or solicitor) is judged by the standard of a reasonably competent member of that profession, not the average person. The assessment is informed by expert evidence of accepted professional practice.

Key Term: Bolam test
A professional is not negligent if they act in accordance with a practice accepted as proper by a responsible body of professionals in that field.

Professional practice is persuasive but not conclusive. The court retains its evaluative role.

Key Term: Bolitho principle
Even if a body of professional opinion supports the defendant’s actions, the court may find them negligent if the opinion is not logically defensible.

Thus, where expert opinions conflict, the court examines whether the reasoning supporting the defendant’s approach is sound and considers risks and benefits in a logically defensible way. Compliance with professional guidelines or protocols is relevant evidence but not dispositive; equally, a departure from a guideline may be reasonable where the circumstances justify it.

In medical cases involving consent, the standard is not set by medical practice but by patient autonomy.

Key Term: material risk
A risk is material if a reasonable person in the patient’s position would likely attach significance to it, or if the doctor knows the patient would.

Under this approach, a doctor must take reasonable care to inform the patient of material risks and reasonable alternatives. Limited exceptions apply (such as where disclosure would be seriously detrimental, or in genuine emergencies), but the focus is on what the patient would consider significant, rather than what practitioners customarily disclose.

Worked Example 1.2

A consultant chooses between two accepted treatments. A responsible body of expert opinion supports the option chosen, but it carries a slightly higher risk of a rare complication than the alternative. The reasoning is that the chosen option avoids other material downsides for this patient.

Question: Is the consultant likely to meet the professional standard?

Answer:
Yes, if the supporting opinion is a responsible one and the reasoning is logically defensible. Under Bolam the presence of a responsible body supports the conduct, and under Bolitho the court tests whether the body’s reasoning weighs risks and benefits in a coherent way. Separate from treatment choice, the consultant must also have taken reasonable care to inform the patient of material risks and alternatives (Montgomery).

Unskilled Defendants and Learners

A learner or inexperienced person is held to the same standard as someone competent in that activity. For example, a learner driver is judged by the standard of a qualified driver, and a newly qualified professional is judged by the standard appropriate to the post they occupy. Lack of experience is not a defence.

Worked Example 1.3

A learner driver collides with a lamppost during a lesson, injuring the instructor. The learner says, “I am inexperienced.”

Question: Does inexperience reduce the standard?

Answer:
No. A learner is expected to meet the standard of the reasonably competent driver. The question is whether that standard was met on the facts.

Children

Children are judged by the standard of a reasonable child of the same age, not by adult standards. What risks a child ought reasonably to have appreciated depends on their age and development.

Emergencies

Circumstances of urgency are relevant to breach. Where a defendant must act rapidly (for example, to respond to an emergency), the law recognises that less deliberation is possible. The standard is not suspended: reasonable care still applies, calibrated to the urgency and social utility of the conduct. Emergency responders remain subject to the ordinary standard of care, viewed in the real pressures under which they acted.

Illness and unexpected incapacity

Where a defendant is suddenly and unforeseeably incapacitated (for example, an unanticipated medical event at the wheel), a failure to meet the ordinary standard may not amount to breach. Where early warning signs are experienced and ignored, however, continuing to drive or to undertake a risky activity may fall below the required standard. The main questions are foreseeability of impairment and what the reasonable person would have done as the situation unfolded.

Worked Example 1.4

A driver experiences sudden, unforeseeable hypoglycaemia and moments later loses control, causing a collision.

Question: Is the driver in breach?

Answer:
Likely not. If there were no warning signs, sudden incapacity can excuse an apparent failure to meet the ordinary standard. If, however, early symptoms arose and a reasonable driver would have stopped, continuing would fall below the standard.

The State of Knowledge at the Time

Defendants are judged by what was known or reasonably discoverable at the time of the alleged breach—not with hindsight. The law is concerned with reasonable foreseeability at the time. Where a risk was not reasonably known, and there was no reason to investigate further or to take additional precautions, failing to guard against it is not negligent. Conversely, where risks were known (or ought reasonably to have been identified), safeguards should reflect that knowledge.

This principle applies across contexts. For example, clinical practice is judged by the body of knowledge and accepted techniques at the time; employers assess workplace risks by reference to then-current awareness (including obvious and well-documented hazards); and designers consider the then-applicable standards and information. The “state of the art” defence belongs to statutory product liability; in negligence the focus is always on what the reasonable person would have known or found out at the time.

Worked Example 1.5

A hospital uses a sterilisation method that is later found to allow bacteria through invisible cracks. At the time, no one knew this risk.

Question: Was the hospital negligent for not using a different method?

Answer:
No. The hospital cannot be blamed for failing to guard against a risk that was not known or discoverable at the time.

Proving Breach of Duty

The claimant must prove, on the balance of probabilities, that the defendant breached their duty. Evidence may include eyewitness testimony, documents, expert reports, industry guidance, and inferences drawn from the circumstances. Sometimes events by their very nature point to negligence, even if the precise mis-step cannot be identified.

Key Term: res ipsa loquitur
A doctrine allowing the court to infer negligence from the mere occurrence of an accident, where the cause is unknown, the thing causing harm was under the defendant’s control, and such accidents do not normally happen without negligence.

If the three conditions are met—unknown specific cause, control by the defendant, and an accident of a kind that ordinarily does not occur without carelessness—the court may infer negligence. This does not reverse the legal burden of proof, which remains with the claimant, but it places an evidential onus on the defendant to provide a plausible non-negligent explanation. Where the defendant shows that the accident may have occurred without negligence, the inference may be rebutted. Where the actual cause is known from direct evidence, res ipsa loquitur is generally unnecessary and inappropriate.

Typical scenarios where res ipsa loquitur may assist include unexplained injuries under anaesthesia, falling objects from premises under the defendant’s control, and unbraked vehicles rolling where systems and parking were within the defendant’s control. It will not generally assist where multiple actors or external forces could have caused the harm and control is not uniquely attributable to the defendant, or where credible, specific explanations show that negligence was not more likely than not.

A separate evidential shortcut arises from criminal convictions.

Key Term: Civil Evidence Act 1968 (s 11)
A criminal conviction for an offence involving negligence can be used as evidence of breach in a civil claim, shifting the burden to the defendant to show they were not negligent.

A conviction is admissible proof that the defendant committed the offence, so in a civil claim arising from the same facts it is powerful evidence of breach. The defendant may seek to displace this by showing why civil liability should not follow on the facts (for example, where causation is disputed, or where the civil standard is not met notwithstanding the conviction). Driving convictions for careless or dangerous driving commonly engage section 11 in personal injury litigation. A conviction for gross negligence manslaughter is similarly potent in civil proceedings arising from the same events.

Worked Example 1.6

A patient is injured during surgery, but the exact cause is unknown. The surgical instruments and environment were under the hospital’s control.

Question: Can the patient rely on res ipsa loquitur?

Answer:
Yes. If the injury would not normally occur without negligence and the hospital had control, the court may infer negligence unless the hospital can provide a non-negligent explanation.

Worked Example 1.7

A defendant is convicted of driving without due care and attention after colliding with a cyclist. In a civil claim brought by the cyclist, the defendant argues that the cyclist swerved unexpectedly.

Question: What is the effect of the conviction?

Answer:
The conviction is admissible evidence under section 11 that the defendant drove carelessly. The evidential burden shifts to the defendant to show, on the civil standard, why they were not negligent in the civil sense (for example, because an unforeseeable swerve was the sole cause). The legal burden remains with the claimant, but the conviction is a strong starting point.

Summary

Key Point Checklist

This article has covered the following key knowledge points:

• Breach of duty is assessed by comparing the defendant’s conduct to the objective standard of the reasonable person, not their personal standards.
• The standard of care reflects a balance of factors: likelihood and seriousness of harm, the cost and practicality of precautions, social value, and the relevance (but non-conclusiveness) of common practice.
• Professionals are judged by the Bolam test, subject to the Bolitho logic check; disclosure of risks in medical treatment is governed by materiality from the patient’s position.
• A learner’s or unskilled defendant’s inexperience is not a defence; a newly qualified professional is judged by the standard required of the post they occupy.
• Children are judged by the standard of a reasonable child of the same age.
• Emergencies and unexpected incapacity are part of the factual matrix: the standard remains one of reasonable care in the circumstances.
• Defendants are judged by knowledge reasonably available at the time, not with hindsight.
• Claimants must prove breach on the balance of probabilities, but may invoke res ipsa loquitur where the cause is unknown and the accident speaks of negligence.
• A relevant criminal conviction is admissible as proof of the offence under section 11 of the Civil Evidence Act 1968 and is strong evidence of breach in related civil proceedings.

Key Terms and Concepts

• breach of duty
• standard of care
• Bolam test
• Bolitho principle
• material risk
• res ipsa loquitur
• Civil Evidence Act 1968 (s 11)