Deuteronomy 16:20

"Justice, justice thou shalt follow" - Seek good courts.

Upright and perfect judgment in truth shalt thou follow, that you may come to inherit the land which the Lord your God will give you.

Justice, justice Scripture addresses the litigants. The word appears twice: because one must pursue justice, whether it be to one’s gain, or to one’s loss; or the repetition denotes “time after time” — all the days of your life; or for emphasis.

Scripture addresses those who are entering the land in the phrase so that you may live;

and Scripture addresses their descendants in the phrase and inherit (meaning, that the inheritance will endure). The first cases that the judges must examine will be those involving the most widespread forms of idolatry. You must not plant for yourself an asherah for this was an idolatrous practice (as in “…in the gardens, behind one in the interior” [Isaiah 66: 17]).

JUSTICE, JUSTICE SHALT THOU PURSUE. “Go to seek a reliable court. THAT THOU MAYEST LIVE, AND INHERIT THE LAND. The appointment of qualified judges is of sufficient [importance] to sustain Israel and to settle them upon their Land.” This is Rashi’s language quoting from the Sifre. 144. The reason for the repetition [of the word “justice”] is to indicate that the judges should judge the people with righteous judgment, and you must also pursue justice constantly by going from your place to the place of the great Sages: “after Rabban Yochanan ben Zaccai to Jabneh; after Rabbi [Yehudah Hanasi] to Beth Shearim.”
And Rabbi Abraham [ibn Ezra] commented: “Justice, justice. It is mentioned twice in order to indicate that one should pursue justice whether it would be to his advantage or loss. Or [it may be mentioned] one time after another for emphasis.” But in the Midrash of Rabbi Nechunya ben Hakanah the Rabbis interpreted it by way of a secret. They said: “Justice — this is His attribute of justice in the world, as it is said, Justice, justice shalt thou pursue. After that it is written, that thou mayest live, and inherit the Land. If you will judge yourself [knowing whence you came, and whither you are going, and before Whom you are about to give account and reckoning] you will live. If not, He will judge you and affirm [His judgment over you] against your will. And why is justice mentioned twice? Because it is written, from the brightness before Him.. The two terms brightness and fire thus refer to these two aspects of justice (Abusaula). The first justice refers to actual justice, this being the Divine Glory, as it is written, righteousness lodges in her. And what is the second justice? It is that which frightens the righteous” [making them fearful that perhaps they do not merit the World to Come]. And there [in that Midrash] it is further explained: “Justice is the helmet of salvation upon His head. The ‘head’ denotes only truth, as it is said, The beginning of Thy word is truth, and ‘truth’ is peace, as it is said, Is it not so, if peace and truth shall be in my days? etc.” If so, Scripture is stating here, “You are to judge in your court [to attain] justice, and pursue therein justice and [try to] achieve it, that thou mayest live in the World to Come with the second justice [which alludes to Him] Who is the Higher Justice, this being the great light hidden for the righteous for the Time to Come, and this is also the Might of the Holy One, blessed be He; and thou shalt inherit the Land, the Land of Israel, with the first justice.”

צדק צדק תרדוף. When you are about to put this legislation into practice, the party in charge of appointing such judges is told by Moses to select only those who are already known for their sense of fair play and righteousness. He will have to look for such people all over the tribe. If potential judges do not have all the qualifications which are desirable in a judge, this qualification of fairness is the overriding quality all must possess. This is what the prophet Samuel was told by G’d when he had to look for a replacement of King Sha-ul among the sons of Yishai. (Samuel I 16,7) He was specifically told to ignore external appearances.

למען תחיה וירשת, such qualities are of even greater importance in the Land of Israel, as a failure to comply would result in the ancestral right to that country being denied to you. Compare Isaiah 57,17 who quotes G’d as telling him that a corrupt judiciary [getting away with sinful greed? Ed.] was a primary cause for G’d’s anger at the people.