What does Job mean by "be just with God"?

In Hebrew be just is tsadaq, which Brown-Driver-Briggs gives as "be just, righteous", and in its simple form "have a just cause, be in the right" (tap just). Job uses it three times in this chapter: "how can man be just with God?" (9:2), "Though I were righteous, yet I wouldn’t answer him" (9:15), and "Though I am righteous, my own mouth will condemn me" (9:20). Each time it sits among the words of a dispute: contend and answer (9:3), my judge (9:15), justice and summon (9:19), come together in judgment (9:32). And Job says of such a dispute, "he can’t answer him one time in a thousand" (9:3). The book comes back to the question. Bildad asks, "How then can man be just with God?" (25:4), in the same five Hebrew words as 9:2, and the LORD asks Job, "Will you condemn me, that you may be justified?" (40:8), where justified is this verb.