jikca marde, 'social morals'; ve drani 'standard of correctness'; & pairvu'e 'judgment-virtue' have all been offered. (And zoity. ruv ty.,
not entirely in jest.)
ka pairvu'e (cf. tolpaivu'e, from lujvo list)
I used drazba in broken phone, because I was thinking of "justice"
in the sense of the actual physical action of making things right,
i.e., retribution or restitution. It's clearly a polysemous word in
English, so there's no reason to expect a single lujvo will do it
mi poi pajni cu stidi zo kamdrapai po'u zoigy. the quality of judging right/correct gy.
That's also a meaning of "justice"; the administration of justice generally
requires that a controversy be brought to a judge who judges who are what is
"right" under the circumstances; but then there is also the concomitant fine,
restitution, punishment, or whatever that rectifies (i.e., makes right)
the situation. So if you're talking about the judgment, certainly le ka drapai is better; but after the judge drapais, he must drazba.
In my experience, when people say something like "We demand justice", it is
the drazba they want, not just the drapai.
I almost agree. Yet, from my point of view the drapai (and hence the kamdrapai) covers both, the judgment "what is formally regarded to be right" and the judgment (=the formal order) what has to be done in order to "execute" this judgment. That means that the execution of a judgment is just a consequence, getting its legal/moral/ethical, or what have you, power only from drapai. Having the judgment carried out accordingly is drazba, necessary to fulfill drapai, but this isn't what we call justice, since just being a moreorless "mechanical" act without juridicial power of its own. (Although I'm not talking of criminal law exclusively, nevertheless this picture to point it out: it is not "justice" what people might feel/call when seeing a man hanging from a tree, but just drazba - or maybe even not!).
Then how do you say, "If you want peace, work for justice"?
How about ganai do djica le nu panpi gi le nu gunka be fi -justice cu xamgu
stidi lu ganai do djica lenu panpi gi ko gunka fi lenu lo kamdrapai ba za'irgau li'u
I'm not so sure about ganai... gi... ko.... X implies that I command you to Y? Certainly le nu ko... might make some sense, but that's not what we're saying here. If you want to keep the comand form, I'd suggest:
ja'e .a'o le nu panpi ku ko gunka fi le -justice
(There was a bit of personal back-and-forth here that's not really
relevant, so I'm deleting all of it.)