Learning Outcomes
This article examines the factors courts consider when determining if a defendant has breached their duty of care in negligence, including:
- The objective reasonable person standard informed by reasonable foreseeability at the time of the alleged negligence
- Likelihood of harm and its effect on the intensity of reasonable precautions, including where a risk is so small that further steps are not required
- Magnitude of potential harm and the impact of known vulnerabilities on the level of care even where likelihood is low
- Practicality and proportionality of precautions (cost, difficulty, disruption) and their relationship to the level of risk
- Social utility and context, including emergencies and desirable activities, and relevant statutory guidance (Compensation Act 2006 s 1; SARAH 2015)
- State of knowledge and common practice as relevant but non-determinative considerations within the overall balancing exercise
- Key authorities for structured breach analysis, including Bolton v Stone, Paris v Stepney Borough Council, Latimer v AEC Ltd, Watt v Hertfordshire CC, and related decisions (e.g. Haley v London Electricity Board; Roe v Minister of Health; The Wagon Mound (No 2))
SQE1 Syllabus
For SQE1, you are required to understand how the standard of care in negligence is determined and applied. This includes analysing the specific factors that courts weigh when deciding if a defendant's actions fell below the expected standard, with a focus on the following syllabus points:
- The objective standard of care based on the ‘reasonable person’.
- How the likelihood of harm occurring influences the required standard of care.
- How the potential seriousness (magnitude) of harm affects the standard of care.
- The assessment of the practicality and cost of taking precautions against a risk.
- The balancing exercise undertaken by courts involving these factors.
- Applying these principles to specific factual scenarios to determine breach.
- The distinction between reasonable probabilities and fanciful possibilities when assessing foreseeability of harm.
- How state of knowledge at the time and common practice in an industry are relevant but not conclusive on breach.
- The role of social utility and emergency context in calibrating what precautions are reasonable.
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.
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What is the general standard used by courts to assess whether a defendant has breached their duty of care?
- The standard of the defendant themselves, considering their experience.
- The standard of the highest possible care achievable.
- The standard of the reasonable person in the circumstances.
- The standard set by industry regulations only.
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Which case established that a low probability of harm occurring might mean a defendant is not negligent for failing to take precautions?
- Paris v Stepney Borough Council
- Latimer v AEC Ltd
- Bolton v Stone
- Watt v Hertfordshire County Council
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True or False: If the potential harm is very serious, a defendant might be expected to take precautions even if the risk of that harm occurring is small.
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Which factor considers the cost and difficulty involved in taking steps to eliminate or reduce a risk?
- Magnitude of harm
- Likelihood of harm
- Social utility
- Practicality of precautions
Introduction
Once it is established that a defendant (D) owed a claimant (C) a duty of care (see previous articles on Duty of Care), the next essential element in a negligence claim is to determine whether D breached that duty. A breach occurs when D’s conduct falls below the standard of care expected by law. This article explores the key factors that courts evaluate to decide if the required standard has been met: the likelihood of the harm occurring, the potential severity (magnitude) of that harm, and the practicality of taking preventative measures.
The analysis is a contextual balancing exercise. Courts ask what risks were reasonably foreseeable to a reasonable person at the time, how serious the potential consequences were, what precautions were realistically available, and whether the activity’s social utility affected what would be reasonable. None of these factors is determinative on its own; they interact. The approach recognises that law does not require a counsel of perfection—only reasonable care in the circumstances.
The Standard of Care: The Reasonable Person
The basis for assessing breach of duty is the standard of the reasonable person. The law requires D to behave as a hypothetical reasonable person would have acted in the same circumstances. This is an objective test, meaning it doesn’t usually consider D’s individual shortcomings, like being inexperienced or clumsy.
Key Term: Standard of Care
The level of care expected by law from a person in particular circumstances to avoid causing foreseeable harm to others. In negligence, this is typically the standard of the 'reasonable person'.Key Term: Reasonable Person
A hypothetical, objective legal standard representing an ordinary individual exercising average care, skill, and judgment in conduct. It is used to determine if conduct was negligent.
The standard is not one of perfection; the reasonable person is not expected to foresee every possible risk or take every conceivable precaution. The law balances the need to protect C from harm against the freedom of D to act, and the social utility of D's conduct.
Two further points frame the objective standard:
- State of knowledge: D’s conduct is judged against knowledge reasonably available at the time, not with hindsight. In Roe v Minister of Health [1954] 2 QB 66, clinicians could not be faulted for risks unknown in 1947.
- Common practice: Evidence that an approach was widely adopted is relevant, but not decisive; if the practice itself is unsafe, adherence will not shield a defendant from a finding of breach.
Factors Influencing the Standard of Care
Courts consider several factors when deciding what the reasonable person would have done and whether D’s conduct fell below that standard. This often involves a balancing exercise.
Likelihood of Harm
The greater the probability or likelihood that D's actions could cause harm, the more care the reasonable person would be expected to take. If a risk is very small or far-fetched, the reasonable person might be justified in taking fewer or no precautions.
Key Term: Likelihood of Harm
The probability or chance of injury or damage occurring as a result of the defendant's conduct.
The key case illustrating this principle is Bolton v Stone [1951] AC 850. There, a cricket ball had left the ground only very rarely (about six times in over 30 years), and the court held the club was not negligent given the very low likelihood of harm. By contrast, where escape of balls was frequent (as in Miller v Jackson [1977] QB 966), more substantial precautions were required and negligence was found.
This factor is closely tied to reasonable foreseeability. Courts guard against imposing liability for “fantastic possibilities” and focus on reasonable probabilities (Fardon v Harcourt‑Rivington [1932] All ER Rep 81).
Foreseeability can adjust with context. In Haley v London Electricity Board [1965] AC 778, digging works in a public pavement required extra precautions because it was reasonably foreseeable that blind pedestrians might use the route; the likelihood of harm to such users was sufficient to require more than minimal measures.
Worked Example 1.1
A cricket club has a ground surrounded by a high fence. Over many years, cricket balls have only very rarely been hit out of the ground onto the adjacent quiet road. On one occasion, a ball is hit out and strikes a pedestrian walking past. Is the cricket club likely to be in breach of duty?
Answer:
Applying the principle from Bolton v Stone, the club is unlikely to be in breach. Although harm was foreseeable, its likelihood was extremely low. A reasonable person might deem it acceptable not to take further, potentially expensive, precautions (like raising the fence even higher) against such a small risk.
Worked Example 1.2
A utilities contractor leaves a trench across a pavement with only slim wooden barriers. The area is used by the general public, including a route known to be frequented by blind pedestrians to reach a bus stop. At dusk, a blind pedestrian falls into the trench and is injured. Has the contractor likely breached the duty of care?
Answer:
Yes. In line with Haley v London Electricity Board, it was reasonably foreseeable that blind pedestrians would use the pavement. The likelihood of harm to such users demanded sturdier precautions (e.g., proper barricades and tactile warnings). Minimal barriers were inadequate, so the contractor likely fell below the reasonable standard.
Magnitude of Harm
This factor relates to the seriousness or severity of the potential injury or damage if the risk materialises. Even if the likelihood of harm is low, if the potential consequences are very serious, the reasonable person would be expected to take greater precautions.
Key Term: Magnitude of Harm
The potential severity or seriousness of the injury or damage that could result if a risk materialises.
The principle is demonstrated in Paris v Stepney Borough Council [1951] AC 367. There, the employer knew the claimant was blind in one eye; the risk of a small metal chip injuring his good eye, although improbable, carried catastrophic consequences (total blindness), and goggles should have been provided.
Seriousness includes both the nature of the injury and its impact on the particular claimant where vulnerability is known. While the eggshell skull rule typically affects damages (defendants take claimants as they find them), knowledge of specific vulnerability can raise the standard of care at the breach stage: where D knows or ought to know that injury could have extreme consequences for C, greater precautions are reasonable.
Magnitude also applies in public settings. A low probability risk that could result in fatal injury will, in many contexts, call for robust measures even if such risk rarely materialises.
Worked Example 1.3
An employee at a garage has only one functioning eye, a fact known to his employer. The employer does not provide safety goggles for tasks like chipping metal, although the risk of eye injury for such tasks is generally considered low for workers with normal vision. The employee suffers an injury to his good eye, resulting in total blindness. Is the employer likely to be in breach of duty?
Answer:
Yes, the employer is likely in breach. Applying the principle from Paris v Stepney Borough Council, although the likelihood of injury might have been low, the magnitude of potential harm to this specific employee (total blindness) was extremely high. The reasonable employer, knowing the employee's vulnerability, should have taken the simple precaution of providing goggles.
Worked Example 1.4
A local authority operates a shallow ornamental pond in a park frequented by families with toddlers. There are no barriers, and the water’s edge is accessible at all points. A toddler falls in and drowns. The authority argues the risk was small in a large park and parents must supervise. Has the authority likely breached its duty?
Answer:
A court would weigh likelihood against magnitude. Even if the probability of a toddler falling in was relatively low, the magnitude of harm (fatal drowning) is extremely high. Where simple, practical measures (e.g., partial barriers, strategic planting, clear signage) could significantly reduce risk without undue cost, the authority is likely to be found in breach for failing to take proportionate precautions.
Practicality of Precautions
Courts weigh the likelihood and magnitude of harm against the cost and feasibility of taking precautions to eliminate or reduce the risk. If a risk can be mitigated easily and affordably, a reasonable person would be expected to do so. If the precautions are disproportionately expensive or impractical compared to the risk, the defendant may not be in breach for failing to take them.
Key Term: Practicality of Precautions
The reasonableness of the measures required to eliminate or reduce a risk, considering factors like cost, difficulty, and effectiveness relative to the level of risk.
Latimer v AEC Ltd [1953] AC 643 is a key authority. A factory floor became slippery due to unprecedented flooding mixing oil and water; the employer spread sawdust over much of the floor but ran out. Closing the factory entirely would have been the only way to remove residual risk, but was grossly costly and disruptive. Given the smaller residual risk after reasonable precautions, the employer was not negligent.
This factor requires careful judgment. Where precautions are simple and cheap (e.g., additional warnings, cones or barriers, minor modifications), a failure to implement them is more likely to be unreasonable. Conversely, where only costly and disruptive measures would remain after reasonable steps, the law generally does not require them unless the risk is grave and imminent.
Worked Example 1.5
A factory floor becomes slippery after an unprecedented flood mixes water with oil. The occupiers spread all available sawdust but cannot cover the entire area. Closing the factory would be the only way to completely eliminate the risk of slipping, but this would be very costly. An employee slips on an uncovered patch and is injured. Have the occupiers breached their duty?
Answer:
Unlikely. Following Latimer v AEC Ltd, the occupiers took reasonable precautions (spreading sawdust) given the circumstances. The risk remaining was relatively small compared to the significant cost and disruption of closing the factory. The court balanced the risk against the practicality of the only remaining precaution.
Worked Example 1.6
A council’s gym has cardio machines serviced biannually by independent contractors. The council maintains routine inspection logs. A pedal arm fails between service visits and injures a user. Minor measures (e.g., daily visual checks of high‑use equipment) could have caught early signs of failure. Is the council likely in breach for not closing the gym or increasing service frequency?
Answer:
A court will assess proportionality. Closing the gym or greatly increasing service frequency may be impractical relative to the risk if biannual servicing and routine checks are reasonable. However, if inexpensive, practical measures (e.g., simple daily checks) could materially reduce the risk, failure to implement them may be negligent. Breach is less likely if the council had a reasonable inspection regime commensurate with usage and known risks.
Exam Warning
Remember that these factors are weighed together. A very low likelihood of harm (Bolton v Stone) might be outweighed by a very high magnitude of potential harm (Paris v Stepney), especially if precautions are simple and cheap. Conversely, even a significant risk might not lead to liability if the necessary precautions are prohibitively expensive or impractical (Latimer v AEC). Courts focus on reasonable probabilities, not fanciful possibilities (Fardon). State of knowledge at the time is critical—hindsight must be avoided (Roe). Where risks are small but the cost of avoiding them is essentially nil, failure to take the precaution is more likely to be unreasonable (see The Wagon Mound (No 2) on balancing small risks against low‑cost precautions).
Social Utility of the Defendant's Conduct
The purpose or social value of the defendant's activity is also relevant. If the defendant's actions serve a socially useful purpose, the courts may be more lenient regarding the risks taken.
This consideration is prominent in emergency situations. In Watt v Hertfordshire County Council [1954] 1 WLR 835, the urgency of saving a life justified taking some abnormal risks in transporting equipment, but care still had to be reasonable: social utility reduces, rather than removes, the standard of care.
Activities in the public interest can justify tolerating a higher level of risk if the precautions would seriously undermine the activity’s feasibility (Daborn v Bath Tramways Motor Co Ltd [1946] 2 All ER 333). That said, social utility is not a shield for carelessness; emergency responders must still obey reasonable safeguards (e.g., using lights and sirens and slowing at red signals).
The Compensation Act 2006, s 1, allows courts considering negligence claims to have regard to whether imposing liability might prevent desirable activities from being undertaken or discourage people from participating in them. The Social Action, Responsibility and Heroism Act 2015 (SARAH Act) further requires courts to consider whether the defendant was acting for the benefit of society, demonstrating a predominantly responsible approach, or acting heroically in an emergency. While reinforcing the common law position, these Acts emphasise the importance of social context.
Revision Tip
Think about emergency services. In Watt v Hertfordshire County Council [1954] 1 WLR 835, the risk of injury in transporting unsecured heavy lifting gear was justified by the emergency situation (saving a life). However, this does not give carte blanche; emergency services must still act reasonably in the circumstances.
Balancing the Factors
Determining breach of duty invariably involves balancing these factors. The court asks what precautions the reasonable person, considering the likelihood and magnitude of harm, the cost/practicality of precautions, and the social utility of the activity, would have taken. If D’s conduct fell short of this standard, they have breached their duty.
A structured approach helps:
- Identify the risk and assess its likelihood (how often? how probable?) and who might be affected (including vulnerable users reasonably foreseeable in the setting).
- Consider the magnitude of potential harm (minor injury vs catastrophic harm).
- List available precautions and evaluate their practicality (cost, difficulty, disruption, effect on activity) and effectiveness in reducing the risk.
- Note social utility or emergency context and whether precautions would significantly hinder desirable activity.
- Consider state of knowledge at the time and whether common practice aligns with safety; practice can inform but not conclude the analysis.
- Decide whether, balancing all factors, the defendant acted as a reasonable person would.
The balancing concept is reflected in cases like The Wagon Mound (No 2) [1966] 2 All ER 709 (PC): where a small risk can be eliminated at minimal cost, failing to do so is unreasonable; where only burdensome precautions remain in the face of low risk, not taking them may be reasonable (Latimer).
Revision Tip: Balancing Factors
In problem questions, identify each relevant factor presented in the facts. Analyse the likelihood and potential seriousness of the harm. Consider what precautions could have been taken and how practical/costly they were. Mention social utility if relevant. Conclude by explaining how a court would likely balance these factors to determine if the reasonable person standard was met.
Key Point Checklist
This article has covered the following key knowledge points:
- Breach of duty in negligence means falling below the standard of care required by law.
- The standard is generally objective: that of the reasonable person, judged by what was reasonably foreseeable at the time.
- Courts consider several factors to determine the standard in specific circumstances.
- Likelihood of Harm: Higher probability requires more care; courts focus on reasonable probabilities, not fanciful possibilities.
- Magnitude of Harm: Greater potential severity requires more care; known vulnerabilities raise the standard expected.
- Practicality of Precautions: Risk is balanced against the cost, difficulty, and effectiveness of preventative measures; inexpensive, effective precautions are more likely required.
- Social Utility: The purpose of the defendant's activity can influence the expected standard, especially in emergencies; social utility reduces but does not remove the need for care.
- State of knowledge and common practice are relevant but do not conclusively determine breach.
- These factors are weighed together in a balancing exercise.
- Relevant legislation (Compensation Act 2006, SARAH Act 2015) reinforces consideration of social context for desirable and heroic activities.
Key Terms and Concepts
- Standard of Care
- Reasonable Person
- Likelihood of Harm
- Magnitude of Harm
- Practicality of Precautions