a list of 42 different factors used by U.S. courts to determine whether a duty of care exists. The Tennessee Court of Appeal has also recently followed the California Supreme Court's lead by citing Cabral for the proposition that duty determinations must be made at the highest level of factual generality. Measurement Once a duty exists, the plaintiff must show that the defendant breached it. This is generally treated as the second element of negligence in the United States. Breach involves testing the defendant's actions against the standard of a reasonable person, which varies depending on the facts of the case. For example, physicians will be held to reasonable standards for members of their profession, rather than those of the general public, in negligence actions for medical malpractice. In turn, once the appropriate standard has been found, the breach is proven when the plaintiff shows that the defendant's conduct fell below or did not reach the relevant standard of reasonable care. However, it is possible that the defendant took every possible precaution and exceeded what would have been done by any reasonable person, yet the plaintiff was injured. If that is the case, then as a matter of law, the duty of care has not been breached and the plaintiff cannot recover in negligence. This is the key difference between negligence and strict liability; if strict liability attaches to the defendant's conduct, then the plaintiff can recover under that theory regardless of whatever precautions were taken by the defendant. Examples Products Product liability was the context in which the general duty of care first developed. Manufacturers owe a duty of care to consumers who ultimately purchase and use the products. In the case of Donoghue v Stevenson [1932] AC 562 of the House of Lords, Lord Atkin stated: Land At common law, in the case of landowners, the extent of their duty of care to those who came on their premises varied depending on whether a person was classified as a trespasser, licensee, or invitee. This rule was eventually abolished in some common law jurisdictions. For example, England enacted the Occupiers Liability Act 1957. Similarly, in the 1968 landmark case of Rowland v. Christian, the Supreme Court of California replaced the old classifications with a general duty of care to all persons on one's land, regardless of their status. After several highly publicized and controversial cases, the California Legislature enacted