Ratio decidendi is a Latin phrase meaning "the reason for the decision." The ratio decidendi is "[t]he point in a case which determines the judgment" (see Black's Law Dictionary, page 1135 (5th ed. 1979)) or "the principle which the case establishes" (see Barron's Law Dictionary, page 385 (2d ed. 1984)). It is a legal phrase which refers to the legal, moral, political, and social principles used by a court to compose the rationale of a particular judgment. Unlike obiter dicta, the principles of judgment for ratio decidendi stand as potentially binding precedent, through the principle of stare decisis. This page lists direct English translations of common Latin phrases, such as veni vidi vici and et cetera. ... link title Blacks Law Dictionary, 7th edition Blacks Law Dictionary has traditionally been regarded as the definitive legal dictionary for the law of the United States. ... A court is an official, public forum which a sovereign establishes by lawful authority to adjudicate disputes, and to dispense civil, labour, administrative and criminal justice under the law. ... A judgment or judgement (see spelling note below), in a legal context, is synonymous with the formal decision made by a court following a lawsuit. ... Obiter Dictum is a remark or observation made by a judge while issuing a ruling. ... Precedent, sometimes authority, is the legal principle or rule created by a court which guides judges in subsequent cases with similar issues or facts. ... Stare decisis (Latin: , Anglicisation: , to stand by things decided) (more fully, stare decisis et non quieta movere) is a Latin legal term, used in common law to express the notion that prior court decisions must be recognized as precedents, according to case law. ...

The deft deployment of the ratio decidendi is one of the most powerful weapons in the lawyer's armoury. With a proper understanding of the ratio of a precedent, the advocate can in effect force a lower court to come to a decision which that court may be unwilling, on the facts of the case, to make. Precedent, sometimes authority, is the legal principle or rule created by a court which guides judges in subsequent cases with similar issues or facts. ...

The search for the ratio of a case is akin to a process of mind-reading. One searches the judgment for the abstract principles of law which have led to the decision and which have been applied to the facts before the court. All decisions are, in the common law system, decisions on the law as applied to the facts of the case. Academic or theoretical points of law are not usually determined. Occasionally a court is faced with an issue of such overwhelming public importance that the court will pronounce upon it without deciding it. Such a pronouncement will not amount to a binding precedent, but is instead called an obiter dictum). The ability to isolate the abstract principle of law in the vehemently pragmatic application of that abstraction to the facts of a case is one of the most highly prized legal skills in the common law system. The lawyer is searching for the principles which underlined and underlay the court's decision. This article concerns the common-law legal system, as contrasted with the civil law legal system; for other meanings of the term, within the field of law, see common law (disambiguation). ... Law (from the late Old English lagu of probable North Germanic origin) in politics and jurisprudence, is a set of rules or norms of conduct which mandate, proscribe or permit specified relationships among people and organizations, intended to provide methods for ensuring the impartial treatment of such people, and provide... Precedent, sometimes authority, is the legal principle or rule created by a court which guides judges in subsequent cases with similar issues or facts. ... Obiter Dictum is a remark or observation made by a judge while issuing a ruling. ... This article concerns the common-law legal system, as contrasted with the civil law legal system; for other meanings of the term, within the field of law, see common law (disambiguation). ...

The difficulty in the search for the ratio becomes acute when, as is often the case in the decisions of the Court of Appeal or the House of Lords, more than one judgment is promulgated. A dissenting judgment on the point is not binding, and cannot be the ratio. However, one will sometimes find decisions in which, for example, five judges are sitting the House of Lords, all of whom purport to agree with one another but in each of whose opinions one is able to discern subtly different ratios. Court of Appeals is the title of certain appellate courts in various jurisdictions. ... This article is about the British House of Lords. ...

An example is the case of Kay v. Lambeth LBC, on which a panel of seven of their Lordships sat, and from whose opinions emerged a number of competing ratios, some made express by their Lordships and others implicit in the decision.

Such interpretative ambiguity is inevitable in any word-bound system. Codification of the law, such as has occurred in many systems based on Roman law, may assist to some extent in clarification of principle, but is considered by some common lawyers anathema to the robust, pragmatic and fact-bound system of English law. Law (from the late Old English lagu of probable North Germanic origin) in politics and jurisprudence, is a set of rules or norms of conduct which mandate, proscribe or permit specified relationships among people and organizations, intended to provide methods for ensuring the impartial treatment of such people, and provide... Roman Law is the legal system of ancient Rome. ... English law is a formal term of art that describes the law for the time being in force in England and Wales. ...