Common law
Common law is a body of law built not from statutes written by legislators, but from the accumulated decisions of judges across centuries. Picture a system where the rulings of courts become the law itself, where each judgment layers onto the ones before it, and where the words spoken in a courtroom today can bind judges a hundred years from now. That is how roughly one-third of the world's population lives under the law today. How did a set of practices developed in the courts of English kings after the Norman Conquest of 1066 become one of the most widespread legal frameworks on earth? What does it mean for a judge to "make" law rather than simply apply it? And why do commercial contracts between companies in Japan, France, and Germany so often choose the law of the state of New York to govern their disputes? Those are the questions at the heart of this story.
Henry II, who became the first Plantagenet king in 1154, did something that would reshape English life for centuries. He created a unified court system common to the entire country, pulling legal authority away from local folk courts, manorial courts, and merchant fairs that had each operated under their own rules. His itinerant judges, numbering around 20 to 30 in the 1180s, traveled from the Curia Regis out to hear disputes across England, then returned to London to compare notes and record their decisions. From those recorded discussions, stare decisis took shape: the idea that a judge should follow what an earlier judge decided when the facts are similar. Before the Norman Conquest in 1066, England's legal business had been scattered across hundreds of local jurisdictions. Henry's reform replaced that patchwork with something that was, at least in theory, common throughout the whole country, giving the system its name. The king's motivation was not purely idealistic. Cases involving forest use, fines, and forfeitures could generate what the sources describe as great treasure for the government, and the eyre courts that traveled the circuits did far more than adjudicate: they supervised local government, raised revenue, and enforced the feudal rights of the crown. Eyres could be so exacting that there were complaints the eyre of 1198 reduced the kingdom to poverty, and Cornishmen fled to escape the eyre of 1233. Henry's ambition also brought him into direct conflict with the church. His effort to extend royal court jurisdiction at the expense of canon law courts famously ruptured his relationship with Thomas Becket, the Archbishop of Canterbury, and Becket's murder in his own cathedral sent a wave of popular outrage against the king. Henry negotiated a settlement with the papacy in May 1172, swearing to go on crusade and effectively overturning the more controversial clauses of the Constitutions of Clarendon. Yet royal influence over ecclesiastical cases continued more quietly, and with considerable success.
Bracton's De Legibus et Consuetudinibus Angliae, "On the Laws and Customs of England", stands as one of the earliest and most significant treatises in common law history. Its author, who died in 1268, was heavily influenced by the division of law found in Justinian's Institutes, and his work traces the early development of case law in the thirteenth century. The first extant Year Book was published that same year, 1268, and the Year Books continued as the principal source of knowledge about developing legal doctrines from the thirteenth century through to the sixteenth. The main sources for the history of common law in the Middle Ages are the plea rolls and the Year Books. The plea rolls were the official court records of the Courts of Common Pleas and King's Bench, written in Latin and organized into bundles by law term: Hilary, Easter, Trinity, and Michaelmas. Those rolls, covering the Courts of Common Pleas, King's Bench, and Exchequer of Pleas from the thirteenth century to the seventeenth, can be viewed online through the Anglo-American Legal Tradition site, hosted by the O'Quinn Law Library of the University of Houston Law Center. The English Court of Common Pleas, established after Magna Carta in 1215, tried lawsuits between commoners in which the monarch had no interest. Its judges sat in open court in the Great Hall of the king's Palace of Westminster during the four terms of the legal year. After the American Revolution, the task of maintaining that written record passed to the new states. Massachusetts became the first state to establish an official Reporter of Decisions, and newer states often turned to the Massachusetts Reports for authoritative precedents when they needed a body of law to build on. The United States federal courts relied on private publishers until after the Civil War, and only began publishing decisions as a government function in 1874. West Publishing, based in Minnesota, became the largest private-sector publisher of law reports in the country.
Oliver Wendell Holmes Jr. cautioned that general principles in both common and constitutional law "arise gradually, in the emergence of a consensus from a multitude of particularized prior decisions." Justice Cardozo put it another way: the common law "does not work from pre-established truths of universal and inflexible validity to conclusions derived from them deductively" but draws its generalizations from particulars. That inductive quality is what makes the common law more malleable than statutory law. Common law courts are not absolutely bound by precedent; when extraordinarily good reason is shown, they can reinterpret and revise the law without waiting for legislative action, adapting to new trends in political, legal, and social philosophy. The process is gradual. Over a decade or more, the law can change substantially but without a sharp break, reducing the disruptive effects that can accompany sudden legislative change. The legislative route, by contrast, is slow and complicated. It requires a bill, a committee system, floor debate, a potential conference committee, a vote, and approval by a head of state. Judicial precedent does not operate uniformly across all courts. In the United States, the federal courts are divided into twelve regional circuits, each with a court of appeals, plus a thirteenth in the Court of Appeals for the Federal Circuit, which hears patent cases and cases against the federal government without geographic limit. Decisions of one circuit court bind the district courts within that circuit, but are only persuasive authority in sister circuits. Most federal courts of appeal operate with panels of three judges, and if panels conflict, the earlier panel decision controls until the full court, sitting en banc with all active judges, overrules it. At the top, courts like the United States Supreme Court always sit en banc; their later decisions control, and older decisions survive only where they do not conflict with newer rulings.
Jeremy Bentham coined the term "judge-made law" as a criticism, attacking what he saw as the legal profession's pretense that judges merely discovered pre-existing custom rather than created new rules. Before Bentham's challenge, the dominant view was William Blackstone's declaratory theory: that common law reaffirmed ancient Anglo-Saxon customs but did not itself make law. Until the early twentieth century, legal dictionaries including Bouvier's Law Dictionary and Black's Law Dictionary still defined common law as "unwritten law," lex non scripta. Edward Coke, Lord Chief Justice in the seventeenth century, had presented the common law as a collection of ancient maxims, many of them inherited from Roman law and stated in Latin even in English decisions. His Institutes of the Lawes of England was the first attempt at a comprehensive compilation of centuries of common law, and lawyers in both England and America learned from his Institutes and Reports until the end of the eighteenth century. Holmes challenged this tradition directly. In a famous article, "The Path of the Law," he called it "revolting to have no better reason for a rule of law than that so it was laid down in the time of Henry IV," and more revolting still if the grounds for that rule had long since vanished and the rule persisted only through "blind imitation of the past." In an 1880 lecture at Harvard, he stated: "The life of the law has not been logic; it has been experience." Holmes went further, arguing that the judge of the future would be "the man of statistics and the master of economics." That prediction took institutional form in the early twentieth century, when Louis Brandeis, later appointed to the United States Supreme Court, became known for loading his legal briefs with policy-driving facts, economics, and extensive appendices presenting data meant to guide judges toward his client's position.
Justice Brandeis famously stated that "in most matters it is more important that the applicable rule of law be settled than that it be settled right." That principle is the foundation of common law's commercial power. Because there is reasonably precise guidance on almost every legal issue, businesses can predict whether a proposed course of action is likely to be lawful or unlawful, and they can act close to the boundaries of the law with some confidence about where those boundaries lie. That predictability explains a striking commercial phenomenon: contracts between companies in Japan, France, Germany, and most other countries frequently specify that disputes will be governed by the law of the state of New York, even when neither party has meaningful contacts with New York, and sometimes when neither has any contacts with the United States at all. Because of New York's history as the United States' commercial center, its common law has accumulated depth and predictability that other American jurisdictions have not yet matched. A similar logic drives American corporations to incorporate under Delaware corporate law; merger agreements, shareholder rights arrangements, and similar corporate contracts routinely include a Delaware choice-of-law clause because of the dense body of corporate case law that state has built up. Where a legal system offers less predictability because it does not consistently follow precedent, fine questions of law must be renegotiated each time they arise, making procedures more protracted and outcomes more uncertain for parties who cannot rely on written legal guidance.
The Napoleonic Code expressly forbade French judges from pronouncing general principles of law, which captures the fundamental difference in philosophy between the two systems. Civil law traces its lineage through the Napoleonic Code back to the Corpus Juris Civilis of Roman law, while common law traces its history to the English courts. In the civil law adversarial arrangement, prosecution and adjudication are separated: a common law court uses an adversarial system where two sides present their cases to a neutral judge. The civil law inquisitorial alternative assigns an examining magistrate to develop evidence and arguments for both sides during the investigation phase, then present a dossier to a panel. That panel's president is therefore not neutral by the time a trial begins. The distinction between the two systems has been blurring. Civil law countries are giving growing weight to jurisprudence that resembles case law, even without treating it as formally binding. Common law countries are increasingly adopting codified frameworks in areas such as bankruptcy, intellectual property, antitrust, banking regulation, securities, and tax law. In the United States, the Uniform Commercial Code has been enacted, with some local variations, in all fifty states, the District of Columbia, Puerto Rico, and the Virgin Islands. A 1982 decision of the European Court of Justice, Srl CILFIT and Lanificio di Gavardo SpA v Ministry of Health, showed the movement going the other direction: a court composed at that time of judges from essentially civil law jurisdictions held that questions it had already answered did not need to be resubmitted, a distinctly common law principle applied in a historically civil law forum.
England first extended its legal system to Wales, then to Ireland, and then to colonies overseas. The British Empire carried the process further, and many former colonies retain the common law system today. When a former British colony became independent, it typically adopted a reception statute, a law by which the new nation formally received the English common law as its default, to the extent not explicitly rejected by the legislature or constitution. Adoption in the newly independent United States was not automatic. Immediately after the American Revolution, there was widespread hostility to anything British, and the common law was no exception. Jeffersonians decried lawyers and their common law tradition as threats to the new republic; they preferred a legislatively enacted civil code under political control rather than judge-made law deliberately insulated from politics. The Federalists argued that common law was the birthright of independence: the natural rights to life, liberty, and the pursuit of happiness were the very rights common law had long protected. Even supporters of the common law acknowledged a practical problem. The best legal libraries before independence had been maintained by Tory lawyers, and those libraries vanished with the loyalists. John Adams, then a lawyer and later president, complained that he suffered very much for want of books. To address this, lawyers in Massachusetts donated their personal collections in 1803 to found a law library, though a Jeffersonian newspaper criticized the effort, warning that the library might carry forward English monarchical legal principles into the new Commonwealth. Today the common law constitutes the basis of legal systems across Australia, Bangladesh, Canada, Ghana, India, Ireland, Israel, Kenya, Malaysia, New Zealand, Nigeria, Pakistan, Singapore, South Africa, the United Kingdom, and the United States, among many others. Scotland maintains a distinct system that blends elements of uncodified civil law with its own common law predating the Treaty of Union with England in 1707, a reminder that even within common law traditions, the particular history of each jurisdiction continues to shape how judges reason and what rules they apply.
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Common questions
What is common law and how does it differ from statutory law?
Common law is a body of law developed primarily through judicial decisions rather than statutes, relying on the principle of stare decisis, meaning courts follow precedents established in previous similar cases. Statutes are generally understood to supersede common law, and legislatures may codify or overrule it, but common law remains the primary source of law in areas such as contract law and the law of torts.
When did common law originate and who developed it?
Common law originated in the practices of the courts of the English kings in the centuries following the Norman Conquest in 1066. Henry II, who became the first Plantagenet king in 1154, institutionalized it by creating a unified court system, sending itinerant judges throughout England and establishing a body of decisions that became binding precedent.
Why do commercial contracts around the world often choose New York or Delaware law?
The law of the state of New York is frequently chosen in commercial contracts because of its depth and predictability, built up through New York's history as the United States' commercial center. Delaware corporate law is similarly chosen for merger, acquisition, and shareholder agreements because of the dense body of corporate case law Delaware has accumulated over time.
What countries use common law today?
Approximately one-third of the world's population lives in common law jurisdictions or mixed systems that integrate common law and civil law. Countries using common law include Australia, Bangladesh, Canada, Ghana, India, Ireland, Israel, Kenya, Malaysia, New Zealand, Nigeria, Pakistan, Singapore, South Africa, the United Kingdom, and the United States, among many others.
What is stare decisis and how does it work in common law courts?
Stare decisis, meaning "to stand by things decided," is the doctrine that courts follow precedents established in previous decisions involving similar facts. In the United States federal system, decisions of a circuit court of appeals are binding on district courts within that circuit, while decisions of one circuit are only persuasive authority in other circuits; the Supreme Court, which always sits en banc, can overrule its own prior decisions.
How does common law differ from civil law systems?
Common law systems place great weight on judicial precedent as a source of law and use an adversarial system where two sides present their cases to a neutral judge. Civil law systems, used in Continental Europe, Mexico, and much of Latin America, trace their lineage to Roman law and the Napoleonic Code; they traditionally give less weight to judicial precedent, and the Napoleonic Code expressly forbade French judges from pronouncing general principles of law.
All sources
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