Ratio decidendi
Latin: The reason for the decision.
Also called: Ratio, Ratio of a case
The principle of law on which a case is decided. It is the binding part of a judgment under the doctrine of precedent, as distinct from obiter dicta.
Explained
Ratio decidendi means the reason for the decision. It is the principle of law, applied to the material facts, that is necessary for the decision of the case. Under the doctrine of precedent, the ratio binds lower courts and, subject to rules on larger and smaller benches, courts of coordinate jurisdiction. Statements of law not necessary for the decision are obiter dicta, which may be persuasive but are not binding in the same way.
In India the binding force of precedent comes from Article 141 of the Constitution, which provides that the law declared by the Supreme Court shall be binding on all courts within the territory of India. What binds is the ratio of the decision, not every observation in it. The Supreme Court has said that the ratio of a judgment is to be found by reading the judgment as a whole, and that a short summary of conclusions at its end must be read in that context.
Two classical tests are used to identify the ratio. Wambaugh's test, sometimes called the reversal or inversion test, takes a proposition of law and inverts it: if the decision would have been different with the inverted proposition, the proposition is part of the ratio; if the decision would be the same, it is not. Goodhart, in his essay Determining the Ratio Decidendi of a Case, proposed that the ratio is found by taking the facts treated by the judge as material, together with his decision on those facts. Where a case has more than one ground, each ground necessary to the decision may form part of the ratio.
The ratio must also be distinguished from a decision given per incuriam, in ignorance of a binding statute or precedent, which does not bind. Examiners test the meaning, the role of Article 141, and the Wambaugh and Goodhart tests.
What the law says
The law declared by the Supreme Court shall be binding on all courts within the territory of India.
Law declared by the Supreme Court binds all courts
For the exam
- Means the reason for the decision: the binding principle of a case.
- Binding effect in India rests on Article 141 of the Constitution.
- Obiter dicta are not binding in the same way, though they may persuade.
- Wambaugh's inversion test; Goodhart's material facts test.
- A decision per incuriam does not bind.
160 questions in the Law Maker question bank use this maxim. Practise Legal Maxims & Jurisprudence questions
Judgments
Related terms
- Obiter dictumA statement in a judgment that is not necessary for deciding the case, and so does not form part of its binding ratio decidendi.
- Stare decisisTo stand by things decided. Courts follow earlier decisions on the same point of law, so that the law remains certain and consistent.
- Per incuriamA decision given in ignorance or forgetfulness of a binding statutory provision or a binding precedent. Such a decision does not bind later courts as a precedent.
- Res judicataA matter directly and substantially in issue that a competent court has heard and finally decided between the same parties cannot be tried again in a later suit (Section 11, CPC).
- Amicus curiaeA friend of the court: a person, usually a senior advocate, whom the court asks to assist it on a question of law or fact, without representing any party.
Further reading
Checked 6 November 2026. Statutory text is quoted from the Bare Acts library, taken from India Code. See the full glossary.