Common law (also known as case law or precedent) is law developed by judges, courts, and similar tribunals, stated in decisions that nominally decide individual cases but that in addition have precedential effect on future cases.〔(【引用サイトリンク】title=Common Law Legal Definition )〕 Common law is a third branch of law, in contrast to and on equal footing with statutes which are adopted through the legislative process, and regulations which are promulgated by the executive branch.
A "common law system" is a legal system that gives great precedential weight to common law,〔Washington Probate, "Estate Planning & Probate Glossary", ''Washington (State) Probate'', (s.v. "common law" ), 8 Dec. 2008:, retrieved on 7 November 2009.〕 so that consistent principles applied to similar facts yield similar outcomes.〔Charles Arnold-Baker, ''The Companion to British History'', s.v. "English Law" (London: Loncross Denholm Press, 2008), 484.〕 The body of past common law binds judges that make future decisions, just as any other law does, to ensure consistent treatment. In cases where the parties disagree on what the law is, a common law court looks to past precedential decisions of relevant courts. If a similar dispute has been resolved in the past, the court is usually bound to follow the reasoning used in the prior decision (this principle is known as ''stare decisis''). If, however, the court finds that the current dispute is fundamentally distinct from all previous cases (called a "matter of first impression"), judges have the authority and duty to make law by creating precedent.〔''Marbury v. Madison'', (5 U.S. 137 ) (1803) ("It is emphatically the province and duty of the judicial department to say what the law is. Those who apply the rule to particular cases, must of necessity expound and interpret that rule. If two laws conflict with each other, the courts must decide on the operation of each.")〕 Thereafter, the new decision becomes precedent, and will bind future courts. ''Stare decisis'', the principle that cases should be decided according to consistent principled rules so that similar facts will yield similar results, lies at the heart of all common law systems.
One third of the world's population (approximately 2.3 billion people) live in common law jurisdictions or in systems mixed with civil law. Common law originated during the Middle Ages in England,〔http://www.britannica.com/EBchecked/topic/188090/English-law ; British History: Middle Ages (【引用サイトリンク】 url = http://www.bbc.co.uk/history/british/middle_ages/henryii_law_01.shtml )〕 and from there was propagated to the colonies of the British Empire, including India, the United States (both the federal system and 49 of its 50 states), Pakistan,〔(【引用サイトリンク】title=Federation of Pakistan v. Bhatti, "''in a common law jurisdiction such as ours''" )〕 Nigeria, Bangladesh, Canada (and all its provinces except Quebec), Malaysia, Ghana, Australia,〔(【引用サイトリンク】title=The Common Law in the World: the Australian Experience )〕 Sri Lanka, Hong Kong, Singapore, Burma, Ireland, New Zealand, Jamaica, Trinidad and Tobago, Cyprus, Barbados,〔(【引用サイトリンク】title=Parliament of Barbados: one of the oldest Constitutions in the Commonwealth )〕 South Africa, Zimbabwe, Cameroon, Namibia, Liberia, Sierra Leone, Botswana, Guyana, and Fiji.
The term ''common law'' has three main connotations and several historical meanings worth mentioning:
===1. Common law as opposed to statutory law and regulatory law ===
Connotation 1 distinguishes the authority that promulgated a law. For example, most areas of law in most Anglo-American jurisdictions include "statutory law" enacted by a legislature, "regulatory law" promulgated by executive branch agencies pursuant to delegation of rule-making authority from the legislature, and common law (connotation 1) or "case law", ''i.e.'', decisions issued by courts (or quasi-judicial tribunals within agencies). This first connotation can be further differentiated into
; (a) pure common law: arising from the traditional and inherent authority of courts to define what the law is, even in the absence of an underlying statute or regulation. Examples include most criminal law and procedural law before the 20th century, and even today, most contract law and the law of torts.
; (b) interstitial common law: court decisions that analyze, interpret and determine the fine boundaries and distinctions in law promulgated by other bodies. This body of common law (connotation 1), sometimes called "interstitial common law," includes judicial interpretation of the Constitution, of legislative statutes, and of agency regulations, and the application of law to specific facts.
===2. Common law legal systems as opposed to civil law legal systems ===
Connotation 2 differentiates "common law" jurisdictions and legal systems from "civil law" or "code" jurisdictions.〔 Common law (connotation 2) systems place great weight on court decisions, which are considered "law" with the same force of law as statutes—for nearly a millennium, common law (connotation 2) courts have had the authority to make law where no legislative statute exists, and statutes mean what courts interpret them to mean. By contrast, in civil law jurisdictions (the legal tradition that prevails, or is combined with common law, in Europe and most non-Islamic, non-common law countries), courts lack authority to act if there is no statute, and judicial precedent is given less interpretive weight (which means that a judge deciding a given case has more freedom to interpret the text of a statute independently, and less predictably), and scholarly literature is given more. For example, the Napoleonic code expressly forbade French judges to pronounce general principles of law.〔"5. The judges are forbidden to pronounce, by way of general and legislative determination, on the causes submitted to them." (Code of Napoleon, Decree of March 5, 1803, Law 5 )〕
As a rule of thumb, common law (connotation 2) systems trace their history to England, while civil law systems trace their history through the Napoleonic Code back to the Corpus Juris Civilis of Roman law.
The contrast between common law and civil law systems is elaborated in "Contrasts between common law and civil law systems" and "Alternatives to common law systems", below.
===3. Law as opposed to equity ===
Connotation 3 differentiates "common law" (or just "law") from "equity".〔〔 Before 1873, England had two parallel court systems: courts of "law" which could only award money damages and recognized only the legal owner of property, and courts of "equity" (courts of chancery) that could issue injunctive relief (that is, a court order to a party to do something, give something to someone, or stop doing something) and recognized trusts of property. This split propagated to many of the colonies, including the United States (see "Reception Statutes", below). For most purposes, most jurisdictions, including the U.S. federal system and most states, have merged the two courts.〔(Federal Rule of Civil Procedure, Rule 2 ) ("There is one form of action—the civil action.") (1938)〕 Additionally, even before the separate courts were merged, most courts were permitted to apply both law (connotation 3) and equity, though under potentially different procedural law. Nonetheless, the historical distinction between "law" (in connotation 3) and "equity" remains important today when the case involves issues such as the following:
* categorizing and prioritizing rights to property—for example, the same article of property often has a "legal title" and an "equitable title," and these two groups of ownership rights may be held by different people.
* in the United States, determining whether the Seventh Amendment's right to a jury trial applies (a determination of a fact necessary to resolution of a "common law" claim)〔"In Suits at common law ... the right of trial by jury shall be preserved, and no fact tried by a jury shall be otherwise reexamined in any Court of the United States, than according to the rules of the common law."〕 or whether the issue will be decided by a judge (issues of what the law is, and all issues relating to equity).
* the standard of review and degree of deference given by an appellate tribunal to the decision of the lower tribunal under review (issues of law are reviewed ''de novo'', that is, "as if new" from scratch by the appellate tribunal, while most issues of equity are reviewed for "abuse of discretion," that is, with great deference to the tribunal below).
* the remedies available and rules of procedure to be applied.
Courts of equity rely on common law principles of binding precedent (connotation 1).
===4. Historical uses ===
In addition, there are several historical uses of the term that provide some background as to its meaning.
In one archaic usage, "common law" refers to the pre-Christian system of law, imported by the Saxons to England, and dating to before the Norman conquest, and before there was any consistent law to be applied. This definition is found or alluded to in some internet dictionaries.〔E.g., (Lectric Law Dictionary ) : That which derives its force and authority from the universal consent and immemorial practice of the people. It is at best obsolete. It is both underinclusive and overinclusive. Lawyers never rely on this definition.〕
"Common law" as the term is used today in common law countries contrasts with ''ius commune''. While historically the ''ius commune'' became a secure point of reference in continental European legal systems, in England it was not a point of reference at all.〔David John Ibbetson, ''Common Law and Ius Commune'' p.20 (2001) ISBN 978-0-85423-165-2〕
The English Court of Common Pleas dealt with lawsuits in which the Monarch had no interest, i.e., between commoners.
Additionally, from at least the 11th century and continuing for several centuries after that, there were several different circuits in the royal court system, served by itinerant judges who would travel from town to town dispensing the King's justice. The term "common law" was used to describe the law held in common between the circuits and the different stops in each circuit. The more widely a particular law was recognized, the more weight it held, whereas purely local customs were generally subordinate to law recognized in a plurality of jurisdictions.
These definitions are archaic, their relevance having dissipated with the development of the English legal system over the centuries, but they do explain the origin of the term as used today.
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