In tort law, a duty of care is a legal obligation that is imposed on an individual, requiring adherence to a standard of reasonable care while performing any acts that could foreseeably harm others. It is the first element that must be established to proceed with an action in negligence. The claimant must be able to show a duty of care imposed by law that the defendant has breached. In turn, breaching a duty may subject an individual to liability. The duty of care may be imposed by operation of law between individuals who have no current direct relationship (familial or contractual or otherwise) but eventually become related in some manner, as defined by common law (meaning case law). Duty of care may be considered a formalisation of the social contract, the implicit responsibilities held by individuals towards others within society. It is not a requirement that a duty of care be defined by law, though it will often develop through the jurisprudence of common law. Development of the general duty of care At common law, duties were formerly limited to those with whom one was in privity one way or another, as exemplified by cases like Winterbottom v. Wright (1842). In the early 20th century, judges began to recognize that the cold realities of the Second Industrial Revolution (in which end users were frequently several parties removed from the original manufacturer) implied that enforcing the privity requirement against hapless consumers had harsh results in many product liability cases. The idea of a general duty of care that runs to all who could be foreseeably affected by one's conduct (accompanied by the demolishing of the privity barrier) first appeared in the judgment of William Brett (later Lord Esher), Master of the Rolls, in Heaven v Pender (1883). Although Brett's formulation was rejected by the rest of the court, similar formulations later appeared in the landmark U.S. case of MacPherson v. Buick Motor Co. (1916) and, in the UK, in Donoghue v Stevenson (1932). Both MacPherson and Donoghue were product liability cases, and both expressly acknowledged and cited Brett's analysis as their inspiration. Scope Although the duty of care is easiest to understand in contexts like simple blunt trauma, it is important to understand that the duty can be still found in situations where plaintiffs and defendants may be separated by vast distances of space and time. For instance, an engineer