Ratio decidendi (plural: rationes decidendi) is a
Latin phrase meaning "the reason (or rationale) for the decision."The ratio decidendi is:"[t]he point in a case which determines the judgment" or"the principle which the case establishes." 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 ratio decidendi is, as a general rule,
binding on courts of lower jurisdiction--through the doctrine of
stare decisis. Certain courts are able to overrule decisions of a court of co-ordinate jurisdiction--however out of interests of
judicial comity they generally try to follow co-ordinate rationes.
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The principles of law applied by a Court upon which a judicial decision is based