Legal Dictionary


Legal Definition of ius

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Definition of ius

Alternative forms


    From an earlier *ious, from Proto-Indo-European *yAus- (“ritual purity; supreme justice”).


iūs (genitive iūris); n, third declension

  1. law, right, duty

    Jus summum saepe summa est malitia (The highest law is often the greatest roguery) - Terence Heautontimorumenos 4.5.43 (translation Benham's Book of Quotations 1948)

  2. court of law

Further reading

Two principal meanings of "Ius"

Ius/jus (Latin "law", "justice", "right") in ancient Roman law, has two principal meanings (cf Fench "droit," German "Recht," English "right", Spanish "Derecho"):

  1. "Law" in the abstract.
    A) ... as distinguished from any specific enactment, the domain of learning, or any personified factor in human history/conduct/social development. Often contrasted with lex or leges, which are the laws. Ius is the law in its broadest sense or its ideal state, above and unaffected by the contingent decrees that the state happens to enact, the leges -- hence the distinction between the English terms “justice” and “legislation.” This division persisted into various regimes not only of civil law regime, and even in the law of the United States, as in the Fourteenth Amendment of the United States Constitution, which distinguishes “due process of law” (singular, as in ius) from “equal protection of the laws” (plural, as in leges).
    B) ... the law taken as a system, an aggregate, a whole -- "the sum total of a number of individual laws taken together."
    C) ... some one particular system or body of particular laws ; as in the phrases "jus civile," "jus gentium," "jus pr"torium."
  2. "A right."
    A) a power, privilege, faculty, or demand inherent in one person and incident upon another
    B) a capacity residing in one person of controlling, with the assent and assistance of the state, the actions of another -- as in the expressions "jus in rem," "jus accrescendi," "jus possessionis."

"Objective" v. "Subjective"

Contemporary continental jurists of the civil law have sought to avoid this ambiguity by calling its first signification "objective" and the second "subjective." Thus Mackeldey (Rom. Law, § 2) says: "The laws of the first kind [compulsory or positive laws] form law [jus] in its objective sense, [jus est norma agendi - law is a rule of conduct.] [By contrast,] The possibility resulting from law in this sense to do or require another to do is law in its subjective sense, [jus est facultas agendi, law is a license to act.] The voluntary action of man in conformity with the precepts of law is called 'justice,' [justitia.]"

Minor meanings

  1. An action. Bract, fol. 3. Or, rather, those proceedings in the Roman action conducted before the pr"tor.
  2. Power or authority. Sui juris In one's own power; independent. Inst. 1, 8, pr.; Bract, fol. 3. Alieni juris, under another's power. Inst. 1, 8, pr.
  3. The profession (ars) or practice of the law. Jus ponitur pro ipsa arte. Bract fol. 2b.
  4. A court or judicial tribunal, (locus in quo redditur jus.) Id. fol. 3.


  1. Wiktionary. Published under the Creative Commons Attribution/Share-Alike License.


1.     warrant
2.     tampering
3.     emtio
4.     amnesty law
5.     magistrates court
6.     lex fori
7.     landed property
8.     lex situs
9.     lex causae
10.     ownership