Standard of care describes the level of skill, diligence and prudence that the law expects from a person in a given situation, commonly in professional negligence, clinical negligence, personal injury and contract claims. It is a benchmark against which a defendant’s conduct is assessed to determine liability for breach of duty.Across England & Wales, Scotland, Northern Ireland and Ireland, the concept is largely derived from case law rather than a single statutory definition. In negligence, the standard of care is usually that of the “reasonable person” in the circumstances, refined for specialists (for example, doctors, solicitors, engineers) by reference to a reasonably competent professional in that field. In medical and professional negligence, courts often apply variants of the Bolam/Bolitho approach or equivalent local jurisprudence.The standard of care is objective, though factors such as foreseeability of harm, seriousness of risk, cost and practicality of precautions, and any specific statutory duties are relevant to what is “reasonable”. Establishing the applicable standard of care, and evidencing whether it was met or breached, is a central issue in litigation strategy, expert evidence and risk management across all UK and Irish jurisdictions.