Justice is truth in action.

[La justice est la vérité en action.]

Joseph Joubert (1754–1824) French moralist, philosopher, essayist, poet

Pensées [Thoughts], ch. 15 “De la Liberté, de la Justice et des Lois [On Liberty, Justice, and Laws],” ¶ 16 (1850 ed.) [tr. Calvert (1866), ch. 12]
    (Source)

(Source (French)). The same (obvious) translation is used by Attwell (1896), ¶ 203.

See also "Grace is beauty in action."