Lewis & Short defines jus, juris with a number of concepts that are related but distinct:

that which is binding or obligatory; that which is binding by its nature, right, justice, duty

I am particularly interested in two concepts here: that of a right and that of a duty.

Using layman's terms, I could think of the two as almost opposites: a duty is what others expect of me, and a right is what I can expect from others.

One simpler way of asking the question is the following: Can I use jus to translate the following English sentences? If so, how do I maintain the important distinction?

  • I have the right to speak.
  • I have the duty to speak.
  • 1
    Interesting question! Any insight here is likely to bring us closer to an answer to the ius sacrum vs. fas question, but this question of great independent interest. I came across two instances of ius est in Ovidius: Metamorphoses 8.733 and Fasti 1.53. It seems they are more about right than duty, contrary to my intuition...
    – Joonas Ilmavirta
    Commented Nov 23, 2016 at 20:54

1 Answer 1


The normal word for "duty" in Latin isn't ius, but officium, and it's well attested for this meaning from Plautus to Suetonius (and later), in prose and poetry alike. Cicero's De Officiis is always translated as On Duties. Might be easier to just post the Lewis & Short definition in full:

II. In gen., an obligatory service, an obligation, duty, function, part, office (so most freq. in prose and poetry of all periods): “nulla vitae pars neque publicis neque privatis neque forensibus neque domesticis in rebus, neque si tecum agas quid, neque, si cum altero contrahas, vacare oflicio potest: in eoque et colendo sita vitae est honestas omnis et in neglegendo turpitudo, etc.,” Cic. Off. 1, 2, 4 sq.: perfectum officium rectum opinor vocemus, quod Graeci κατόρθωμα: hoc autem commune καθῆκον vocant, id. ib. 1, 3, 8; “an id doles, quia illi suum officium non colunt, quom tu tuum facis?” Plaut. Stich. 1, 1, 34; id. ib. 1, 1, 39; id. Pers. 4, 4, 66: “meminisse officium suum,” to remember one's duty, id. Trin. 3, 2, 71.—Also, subject., a sense of duty: “si quis aegre ferat nihil in se esse virtutis, nihil officii, etc.,” Cic. Tusc. 4, 28, 61: “quicquid in eum judicii officiique contuleris,” id. Fam. 10, 1 fin.: “intellegere, utrum apud eos pudor atque officium an timor valeret,” Caes. B. G. 1, 40, 14: “suum facere,” to do one's duty, Ter. Ad. 1, 1, 44: “omnibus officiis amicitiae servatis,” observe all the obligations of friendship, Cic. Fam. 5, 17, 3: “exsequi,” id. Att. 3, 15, 4: “fungi officio,” id. Fam. 3, 8, 3: “satisfacere officio,” to perform, id. Div. in Caecil. 14, 47: “officium suum deserere,” to disregard one's duty, not perform it, id. Off. 1, 9, 28: “discedere ab officio,” id. ib. 1, 10, 32: “deesse officio suo,” id. Fam. 7, 3, 1: “officii duxit,” considered it his duty, Suet. Tib. 11.—Of animals: “canes funguntur officiis luporum,” act the part of, Auct. Her. 4, 34, 46.—Of things: “neque pes neque mens satis suum officium facit,” Ter. Eun. 4, 5, 3: officium corporis, the function or property of a body, Lucr. 1, 336 and 362.

Ius, on the other hand, doesn't really mean "duty", and although L&S says so, they don't give very many examples of it. It rather means "right" or "law." When Cicero talks about natural or divine laws, the sort of "laws" that all people should follow regardless of human laws, he speaks of ius.

In that sense, it's a "duty" in that we must obey it. It's not really "duty" in the sense of "civic duty" or "duties of the magistrate", both of which would use officium instead.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.