XXjus-tis (tsedhaqah; tsedheq; dikaiosune): The original Hebrew and Greek words are the same as those rendered "righteousness." This is the common rendering, and in about half the cases where we have "just" and "justice" in the King James Version, the American Standard Revised Version has changed to "righteous" and "righteousness." It must be constantly borne in mind that the two ideas are essentially the same.
See RIGHTEOUSNESS.
1. Human Justice:
Justice had primarily to do with conduct in relation to others, especially with regard to the rights of others. It is applied to business, where just weights and measures are demanded (Lev 19:35,36; Dt 25:13-16; Am 8:5; Prov 11:1; 16:11; Ezek 45:9,10). It is demanded in courts, where the rights of rich and poor, Israelite and sojourner, are equally to be regarded. Neither station nor bribe nor popular clamor shall influence judge or witness. "Justice, justice shalt thou follow" (Dt 16:20 m; compare 16:18-20; Ex 23:1-3,6-9). In general this justice is contrasted with that wickedness which "feared not God, and regarded not man" (Lk 18:2).
In a larger sense justice is not only giving to others their rights, but involves the active duty of establishing their rights. So Israel waits upon Gods justice or cries out: "The justice due to me (literally, "my justice") is passed away from my God" (Isa 40:27). Yahweh is to show her to be in the right as over against the nations. Justice here becomes mercy. To "seek justice" means to "relieve the oppressed, judge the fatherless, plead for the widow" (Isa 1:17; compare 11:4; Jer 22:15,16; Ps 82:2-4). The same idea appears in Dt 24:12,13; Ps 37:21,26; 112:4-6, where the translation is "righteous" instead of "just."
In this conception of justice the full meaning of the New Testament is not yet reached. It does not mean sinlessness or moral perfection. Job knows the sin in his heart (Job 13:23,26; 7:21), and yet speaks of himself as a just or righteous man (12:4; 13:18). The Psalmist confidently depends upon the righteousness of God though he knows that no man is righteous in Gods sight (Ps 143:1,2; compare 7:8; 18:20-24). It is not a lack of humility or dependence upon God when the Psalmist asks to be judged according to his righteousness. In relation to God, the just, or righteous, man is the one who holds to God and trusts in Him (Ps 33:18-22). This is not the later Judaistic legalism with its merit and reward, where Gods justice is simply a matter of giving each man what he has earned.
The word "justice" does not occur in the New Testament, and in most cases where we find "just" in the King James Version it is changed to "righteous" in the American Standard Revised Version. The idea of justice or righteousness (remembering that these are essentially the same) becomes more spiritual and ethical in the New Testament. It is a matter of character, and Gods own spirit is the standard (1 Jn 3:7; Mt 5:48). The mere give-and-take justice is not enough. We are to be merciful, and that to all. The ideal is righteousness, not rights. As Holtzmann says, "The keynote of the Sermon on the Mount is justitia and not jus."
2. Justice of God:
Gods justice, or righteousness, is founded in His essential nature. But, just as with man, it is not something abstract, but is seen in His relation to the world. It is His kingship establishing and maintaining the right. It appears as retributive justice, "that reaction of His holy will, as grounded in His eternal being, against evil wherever found." He cannot be indifferent to good and evil (Hab 1:13). The great prophets, Isaiah, Micah, Amos, Hosea, all insist upon Yahwehs demand for righteousness.
But this is not the main aspect of Gods justice. Theology has been wont to set forth Gods justice as the fundamental fact in His nature with which we must reconcile His mercy as best we may, the two being conceived as in conflict. As a matter of fact, the Scriptures most often conceive Gods justice, or righteousness, as the action of His mercy. Just as with man justice means the relief of the oppressed and needy, so Gods justice is His kingly power engaged on behalf of men, and justice and mercy are constantly joined together. He is "a just God and a Saviour" (Isa 45:21). "I bring near my righteousness (or "justice") .... and my salvation shall not tarry" (Isa 46:13; compare Ps 51:14; 103:17; 71:15; 116:5; Isa 51:5,6). The "righteous acts of Yahweh" mean His deeds of deliverance (Jdg 5:11). And so Israel sings of the justice, or judgments, or righteousness of Yahweh (they are the same), and proclaims her trust in these (Ps 7:17; 35:23,24,28; 36:6; 140:12,13; 50:5,6; 94:14,15; 103:6; 143:1).
The New Testament, too, does not lack the idea of retributive justice. The Son of Man "shall render unto every man according to his deeds" (Mt 16:27; compare 25:14-46; Lk 12:45-48; Rom 2:2-16; 6:23; 2 Cor 5:10; Col 3:24,25; 2 Thess 1:8,9; Heb 2:2,3; 10:26-31). But Gods justice is far more than this. The idea of merit and reward is really superseded by a higher viewpoint in the teaching of Jesus. He speaks, indeed, of recompense, but it is the Father and not the judge that gives this (Mt 6:1,4,6,18). And it is no mere justice of earth, because the reward transcends all merit (Mt 24:46,47; Mk 10:30; Lk 12:37). This is grace not desert (Lk 17:10). And the parable of Mt 20:1-15 gives at length the deathblow to the whole Judaistic scheme of merit and reward.
And Gods justice is not merely gracious, but redemptive. It not simply apportions rights, it establishes righteousness. Thus, just as in the Old Testament, the judge is the Saviour. The difference is simply here: in the Old Testament the salvation was more national and temporal, here it is personal and spiritual. But mercy is opposed to justice no more here than in the Old Testament. It is by the forgiveness of sins that God establishes righteousness, and this is the supreme task of justice. Thus it is that God is at the same time "just, and the justifier of him that hath faith in Jesus" (Rom 3:26). "He is faithful and righteous (or "just"; see the King James Version) to forgive us our sins, and to cleanse us from all unrighteousness" (1 Jn 1:9).

LITERATURE.
See Comm., and Biblical Theologies under "Justice" and "Righteousness," and especially Cremer, Biblical-Theol. Lex. of New Testament Greek
Harris Franklin Rall