Duhaime's Law Dictionary

Ubi Eadem Ratio, Ibi Idem Jus Definition:

Latin: Where there is the same reason, there is the same law

The Latin maxim that buttresses the sugestion that the law is based upon, inseperable from, and always a reflection of reason.

Also, where there is common sense, there is the same law.1

The ever-reliable Herbert Broom, in the 1939 edition of his treatise on legal maxims provides a good description of this maxim:

"Ubi eadem ratio ibi idem jus - Like reason doth make like law.

"The law consists, not in particular instances and precedents, but in the reason of the law. For reason is the life of the law. Nay, the common law itself is nothing else but reason ; which is to be understood of an artificial perfection of reason, acquired by long study, observation, and experience, and not of every man's natural reason."

At footnote #13 of the District Court of Appeal of Florida reasons for judgment in O'Hara v State:

"Ubi eadem ratio ibi; idem jus; et de similibus idem est judicium. Where there is the same reason, there is the same law; and where there are similar situations, the judgment is the same."


  • Broom, Herbert, A Selection of Legal Maxims Classified and Illustrated, 10th Ed., (London: Sweet & Maxwell Limited, 1939), pages 94.
  • NOTE 1: Riasanovksy, V.A., Application and the Interpretation of the Norms of Law, 22 Chinese Social and Political Science Review 291 (1938-1939)
  • O'Hara v State, 448 So. 2d 524 (1984)

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