Ratio decidendi (plural rationes decidendi) is a Latin phrase meaning “the reason for the decision.” Ratio decidendi refers to the legal, moral, political and social principles on which a court’s decision rests. It is the rationale for reaching the decision of a case. It is binding on lower courts through the principle of Stare decisis. Ratio decidendi is a helpful tool for a lawyer.
Ratio is a ruling on a point of law and the decision on a point of law depends on facts of a case. Culling out ratio from a judgment is difficult. A thorough reading of an entire judgment is required to identify a ratio. Ration decidendi can be determined or identified in the following ways: