Reasonable Person Test CASES

In English negligence law, the reasonable person (historically, the “reasonable man”) is the objective yardstick for breach of duty. It asks what an ordinarily prudent person would have done in the circumstances as they reasonably appeared at the time. The standard is impersonal: it does not bend to a defendant’s inexperience, anxiety or personal habits. It also is not perfection – reasonable people take sensible precautions, not every imaginable one.

Definition and principles

The court decides breach by weighing the foreseeability and probability of harm, the seriousness of potential injury, the cost and practicality of precautions, and the social utility of the activity. Compliance with industry practice or guidance is relevant but not conclusive; equally, departure from a guideline may be reasonable if justified by the facts. The assessment is time-sensitive: hindsight is avoided, and the question is what a reasonable person would have foreseen and done before the accident, not after it.

How the standard adapts to context

• Professionals and skilled tasks: where breach turns on clinical or technical skill, the court asks whether the conduct accorded with a responsible body of professional opinion that withstands logical analysis (often discussed under Bolam/Bolitho). This is still an objective inquiry, not a vote among experts.
• Learners and inexperienced actors: a learner is generally held to the same standard as a competent person performing that activity (for example, a learner driver). The law protects those affected by the activity, not the learner’s difficulties.
• Children as defendants: when a child is the alleged wrongdoer, the benchmark is that of a reasonable child of the same age, reflecting capacity and foresight at that stage of development.
• Emergencies and pressured decisions: the standard remains objective, but the court allows for the need to act quickly and the limited information available. A response that is sensible in the moment may be reasonable even if a slower, optimal choice existed.
• Disability and known limits: a person with a relevant, known limitation must take reasonable precautions that someone with that limitation would take; what is unreasonable is proceeding as if no limitation existed.

Evidence commonly used

Judges place weight on contemporaneous documents (risk assessments, maintenance and training records), objective measurements (for example, speeds, decibel readings, inspection intervals), expert reasoning where technical issues arise, and the inherent probabilities of competing accounts. Witness memory is considered, but documents and objective data often carry greater weight.

Common examples

• Road use: adjusting speed and lookout for rain or glare; using lights; leaving sensible stopping distances.
• Workplace safety: providing training and simple, low-cost safeguards where a foreseeable risk exists; documenting inspections and promptly fixing recurring hazards.
• Public spaces and events: setting crowd-control measures that are proportionate to numbers and venue layout; responding to known pinch-points and prior incidents.
• Sports and recreation: participants accept ordinary risks of the game, but reckless play or organisation outside the rules can fall below the reasonable standard.

Relationship to neighbouring tests

Reasonable person vs reasonable user: the former is the negligence benchmark for personal conduct; the latter is a nuisance-specific measure of what interferences land users must tolerate in a locality. They answer different questions. Reasonable person vs Wednesbury irrationality: the negligence standard judges private law breach; Wednesbury/irrationality assesses the lawfulness of public-body decisions and is not a merits-based breach test.

Legal implications

• Breach and defences: if conduct falls below the reasonable-person standard, breach is made out. Contributory negligence uses the same objective lens to assess whether the claimant failed to take reasonable care for their own safety (with allowances for age and emergencies).
• Guidance and custom: industry codes, risk matrices and internal policies inform—but do not fix—the standard. A sensible departure can be reasonable; slavish compliance is not a shield if obvious risks remain.
• Statute and regulation: breaching a regulation is persuasive of negligence but not automatically decisive unless Parliament says so; equally, compliance may still be negligent if the situation calls for more.

Practical importance

For claimants, frame the concrete precautions a reasonable person would have taken and show they were practical and proportionate to a foreseeable risk. For defendants, demonstrate a thought-through system that addressed real risks, explain why further measures were impractical or marginal in benefit, and support this with records and expert reasoning. Keep the analysis rooted in the circumstances as they appeared before the incident and avoid hindsight.

History

Courts once asked what “the man on the Clapham omnibus” would do – a Victorian image for the ordinary, prudent citizen. The phrase is credited to Lord Bowen, first appears in the law reports in McQuire v Western Morning News (1903), and was developed in Hall v Brooklands (1933). Today we use reasonable person, but the older label still appears in judgments and textbooks

See also: Standard of care; Proximity; Reasonable user (nuisance); Contributory negligence; Professional negligence (Bolam test/Bolitho); Risk assessment.