Common Law

“Common law” refers to both judge-made law and to a legal system in which judicial decisions are a source of law. The English legal case Rylands v. Fletcher ( UKHL 1868 ) is a common law decision because the House of Lords claimed that the legal foundations for its ruling were provided by a series of judicial decision in cases with similar facts dating from “time immemorial.” Brown v. Board of Education, 347 U.S. 483 ( 1954 ), is not a common law decision because the Supreme Court of the United States claimed that the legal foundation for its ruling was a constitutional enactment, in that instance the equal protection clause of the Fourteenth Amendment. The United States and the United Kingdom are common law countries because judicial decisions are independent sources of law in those polities. France and China are not common law countries because all judicial decisions in those polities must ultimately be based on statutes, constitutions, or other official decrees from the legislative or executive branches of government.

Rylands v. Fletcher, a well known and frequently taught example, illustrates common law decision-making and practice. John Rylands built a reservoir on his land and negligently undermined a dam. This caused considerable flooding of a mine owned by Thomas Fletcher, who sued Rylands for damages. Rylands defended by asserting he was entitled to use his property as he wished and that neither he nor his workers had ever physically entered Fletcher's property. The House of Lords nevertheless found a trespass. When ruling that Rylands had to pay damages to Fletcher, they declared that “the person who for his own purposes, brings on his land and collects and keeps there anything likely to do mischief if it escapes, must keep it in at his peril; and if he does not do so, is prima facie answerable for all the damage which is the natural consequence of its escape.” Lord Cairns, the Lord Chancellor who issued the opinion, derived that rule from previous judicial decisions that concerned liability when cattle escaped and ate corn or grass on another person's property. He did not cite any statute or constitutional law as legal authority. The relevant law consisted entirely of previous judicial decisions in cases involving similar fact patterns. Lord Cairns reasoned that if property holders had to pay damages when their cattle damaged another person's property, they should pay damages when their attempts to improve their property caused damage to another person's property. Subsequent judicial decisions in similar cases, in turn, relied on the principles stated in Rylands v. Fletcher when analyzing the tort liability of landowners whose use of their property caused damage to another person's property.


On the eve of the American Revolution, most law in Great Britain and the colonies was common law. The great English legal treatises that lawyers and their apprentices studied, Edward Coke's Institutes of the Laws of England ( 1628–44 ) and William Blackstone's Commentaries on the Laws of England ( 1765–69 ), were compilations and analyses of common law decisions. Blackstone's analysis of the law of property, for example, was a synthesis of the relevant common law decisions. Statutes were relatively rare in England until the middle of the eighteenth century. Few statutes extensively regulated contracts, property, and torts. Those were mostly matters for judge-made common law. Persons in the eighteenth century could be convicted of common law crimes, infractions that were derived from judge-made law, rather than from parliamentary enactments.

Shelley's Case ( 1581 ) is a famous example of an English common law decision. English monarchs taxed inherited land. To avoid the tax, some testators would will a life estate to their main heir, with the remainder to another person (the “remainderman” would get the property after the main heir died). Shelley's Case closed this loophole. The Court of King's Bench ruled that any person who gained a life estate by conveyance enjoyed full title over the property. This title enabled them to sell the property but also made them subject to taxation. As was the case with Rylands v. Fletcher, Shelley was not based on any previous parliamentary enactment. The court cited only past judicial decisions with similar fact patterns when announcing the relevant property law.

During the nineteenth century, proponents of judge-made common law did battle with proponents of codification, insisting that judges were best able to make law and do justice in light of the particular facts of specific cases, and that the slow pace of judge-made law helped maintain social stability. Proponents of codification insisted that elected officials should make law in a constitutional democracy and that judge-made law rooted in past legal decisions often did not take into account changed circumstances. Common law judging largely survived codification, particularly in the United States. Although far more legislation existed by the New Deal of the 1930s than had been the case before the Civil War ( 1861–1865 ), substantial swaths of law remained judge-made according to common law practices. Many justices adopted the practice of interpreting strictly statutes that were inconsistent with the common law. The result was a legal presumption that legislation was primarily designed to codify previous common law, a presumption that often rendered legislative reforms toothless. Oliver Wendell Holmes Jr.'s The Common Law ( 1881 ), the most influential legal work on private law of its day, detailed how most tort, contract, and property law continued largely as a judicial domain.

Judge Benjamin Cardozo's influential decision in MacPherson v. Buick Motor Company, 217 N.Y. 382 ( 1916 ), demonstrates the method of common law judging, the continued vitality of common law practice in the early twentieth century, and the manner in which more progressive judges attempted to keep common law practices up to date. Donald MacPherson was injured in a traffic accident that was caused by a defective wheel on the Buick he had bought from a local dealer. Rather than sue the local dealer, MacPherson claimed that the Buick manufacturer was responsible for his injuries because the company had not adequately inspected the vehicle. This seemed inconsistent with the existing common law doctrine called “privity of contract.” Under this doctrine, the only person you could sue for a defective product was the person who had sold you the goods. MacPherson could sue his dealer, but even if he was successful in court, the dealer may not have the assets necessary to pay the judgment. Under previously understood notions of privity of contract, MacPherson could not sue Buick, which could afford to pay damages, because he had no contract with Buick.

The common law made an exception, however, in the case of inherently dangerous items such as poisons. Past judicial decisions had ruled that manufacturers of inherently dangerous items could be sued by anyone injured by their negligence. The leading case for this was Thomas v. Winchester, 6 N.Y. 397 ( 1852 ), which Judge Cardozo reinterpreted in MacPherson. He declared “that the principle of Thomas v. Winchester is not limited to poisons, explosives, and things of like nature, to things which in their normal operation are implements of destruction. If the nature of a thing is such that it is reasonably certain to place life and limb in peril when negligently made, it is then a thing of danger” (6 N.Y. at 389). In short, rather than ask whether a car was inherently dangerous, as had past courts, Cardozo asked whether a car with a defective wheel was inherently dangerous. Thus was born the modern law of products liability through judicial reinterpretation of common law past precedents in similar cases rather than by legislation.

The life of the law has not been logic, it has been experience. The felt necessities of the time, the prevalent moral and political theories, intuitions of public policy, avowed or unconscious, even the prejudices which judges share with their fellowmen, have had a good deal more to do than the syllogism in determining the rules by which men should be governed ( Holmes 2009, 1 ).

Other legal historians insist that the common law is more attached to elite interests. Morton Horwitz, a leading advocate of this view, declares that changes in the common law in antebellum America “enabled emergent entrepreneurial and commercial groups to win a disproportionate share of wealth and power in American society” ( 1977, xvi ).


In the early twenty-first century, common law has far less scope than at any previous point in American history. Congress produces far more legislation than at any time in the past. Many states have adopted some version of the Uniform Commercial Code, which regulates business and other contracts. Since the New Deal of the 1930s, administrative agencies have frequently been entrusted with responsibility for making policies that once were the domain of common law property, contracts, and torts. The Federal Trade Commission and other administrative agencies, rather than state and federal courts, for example, make the most important rules for product liability.

Nevertheless, the common law still plays an important role in American governance. The first-year curriculum at most law schools is heavily laden with common law decisions and common law practices. Students learn from common law materials because such common law principles as proximate cause in torts and consideration in contracts still structure American law, even if they are now often embedded in legislation. Common law practices influence statutory and constitutional interpretation. Judicial decisions that mandate the use of strict scrutiny when considering racial classifications via the equal protection clause or those that permit affirmative action in the context of the Civil Rights Act of 1964 are sources of law that must be taken into consideration in subsequent legal decisions. Justice Sandra Day O'Connor in Grutter v. Bollinger, 539 U.S. 306 ( 2003 ), relied heavily on these principles for interpreting the equal protection clause announced in Regents of the University of California v. Bakke, 438 U.S. 265 ( 1978 ), when ruling that the raceconscious admissions program at the University of Michigan School of Law passed constitutional muster. Given the prevalence of common law practice in the United States, the influence of common law judging is likely to be a permanent fixture of governance in the United States even as the realm of the common law is circumscribed.

SEE ALSO Blackstone, William ; Common Law: Legal Systems ; Contract ; Criminal Law ; Property ; Torts .


Blackstone, William. Blackstone's Commentaries: With Notes of Reference to the Constitution and Laws, of the Federal Government of the United States, and of the Commonwealth of Virginia. 5 vols. Edited by St. George Tucker. (1803.) Union, NJ: Lawbook Exchange, 1996.

Cardozo, Benjamin N. The Nature of the Judicial Process. New Haven, CT: Yale University Press, 1921.

Coke, Edward. The Second Part of the Institutes of the Laws of England. (1628–44.) (1809.) Union, NJ: Lawbook Exchange, 2002.

Holmes, Oliver Wendell, Jr. The Common Law. (1881.) Cambridge, MA: Belknap Press of Harvard University Press, 2009.

Horwitz, Morton J. The Transformation of American Law, 1780–1860. Cambridge, MA: Harvard University Press, 1977.

Mark A. Graber
University of Maryland Carey School of Law