Tzedek Tzedek Tirdof

Reish Lakish (Sanhedrin 32b) raises a contradiction between two verses: It is written in one verse: “In justice shall you judge your neighbor” (VaYikra 19:15), and it is written in another verse: “Justice, justice, shall you follow” (Devarim 16:20), with the repetition indicating that it is not enough to merely judge with justice. He continues: How can these texts be reconciled?

Answer #1 (Reish Lakish): One must be extra zealous in a Din in examination of witnesses.
Answer #2 (Rav Ashi): (We resolve the Mishnah and Beraisa like R. Chanina or Rava.) "Tzedek Tzedek Tirdof" teaches to equally pursue Din (letter of the law) or compromise. If two ships encounter each other in a narrow river, if they try to pass at the same time, both will sink. If they go one after the other, both will pass. The same applies to two camels ascending (in opposite directions) the incline to Beis Choron, and they meet at the peak (it is wide enough for only one). If they go at the same time, they will fall. If one waits for the other, both will pass;
Answer #3: "Tzedek Tzedek Tirdof" - go to a good Beis Din, e.g., to R. Eliezer in Lud, or to R. Yochanan Ben Zakai in Beror Chayil.

Additional understandings to “Tzedek Tzedek Tirdof:

1. This refers to the litigants. They should not satisfy themselves with going to an acceptable court. They should even travel a distance to avail themselves of the best judges available. (Rashi) Hence we have the double "tzedek," one referring to the plaintiff, and one to the defendant.
2. This refers to the litigants. Pursue correct judgment and accept it whether you win or lose. (Ibn Ezra)
3. This is a general admonition. Be righteous both in action and in speech. (Rabbeinu Bachyei)
4. This refers to the judge. Do not satisfy yourself with officiating in a court and have litigants come to you. Travel the length and breadth of the land to make yourself available even in small communities, as did the Prophet Shmuel. (Ahavas Tzion)
5. This refers to the judge. Double check to make sure that you have rendered a correct ruling. Otherwise you will lose the assurance that you will remain in the land and be sustained there. (See the Holy Alshich mentioned on 16:18)
6. This refers to the judge. Pursue righteousness from the point of ruling in accordance with the technical laws outlined in the Shulchan Oruch. Also pursue righteousness from the point of ferreting out falsehood in the claims and statements of the litigants, "din m'ru'meh." (Haksav V'hakabalah)
7. This refers to the judge. The Medrash Tanchuma #6 says that we derive from the words "mishpat tzedek" that the judge who rules properly has done two justices. First, he has ruled in favor of the person whose position is the correct one, and with money claims he would receive that which is rightfully coming to him. Second, money that is in the hands of his adversary is taken away, and he does not keep money that is not his. Based on these words "tzedek tzedek tirdofe" means to pursue a double justice, as above. (Baal Avodas Hatzdakah)
8. The Medrash says that based on these words the Rabbis have instituted that there be court sessions on Mondays and Thursdays. The GR"A explains that the order of the seven "kochvei leches," the planetary movement is given a mnemonic of "Ka*TZ*NaSH CHaLaM" for the beginning of the night and "CHaLaM Ka*TZ*Nash" for the beginning of the day. Based on this cycle the beginning of the night leading into Monday is the mazel of Tzedek, and likewise the beginning of the day of Thursday is again Tzedek. Since our verse refers to pursuing a competent court, there is an allusion to Mondays and Thursdays being days of Tzedek, of having court sessions.
9. Our verse tells us that righteous judgment brings in its wake the merit to live. We find in the first verse of Megilas Rus, "Va'y'hi bi'mei shfote hashoftim va'y'hi ro'ov bo'oretz," and it was in the days of the judging of the judges, and there was a famine in the land. The Medrash says that "judging of the judges" means that the judges were corrupt, and their rulings were put under the scrutiny of the people, and this was the judging by the populace of the judges. In its wake a famine came, the opposite of "l'maan tichyeh." (Tosfos Brachah)
10. The Chid"a, in Nachal K'dumim cites the Gemara Rosh Hashanah 4a and P'sachim 8a that says that one who says that this coin is for charity so that the merit of this mitzvah should keep his son alive, or that the merit should bring him to Olam Habo, is considered a complete tzaddik, in spite of having his own agenda. The Tosfos ask from a mishnoh in Pirkei Avos 1:3 "Don't be as servants who serve their master for compensation, etc." If so, how can he be considered a complete tzaddik? The Chid"a differentiates between one who has not yet given a sufficient amount of charity to fulfill his responsibility of tzedakah, and one who has already given sufficiently, but is giving even more. If one hasn't given his full quota, and has his own needs in mind, indeed he is not a complete tzaddik, as per the previously mentioned Mishna. If, however, one has fulfilled his tzedakah obligations and is giving extra, then the personal gains he envisions through the merit of giving tzedakah do not detract from his righteousness, and the Mishna does not apply. This, he points out, is alluded to in our verse. Tzedek tzedek, if you've given tzedakah beyond the basic requirement of tzedakah, then, tirdof, you may do so, even if you pursue (your personal benefit of), l'maan tich'yeh, so that your son may live, or for the purpose of, v'yorashto es ha'aretz, so that you may inherit the permanent land (Olam Haba). This would also explain why the Gemara specifically gives these two examples.
11. This is a general admonition. Do not fall prey to "The end justifies the means." Pursue justice only with justice. (Reb Simchoh Bunim of Parshis'cha)
12. You've done something righteous, "tzedek." Don't sit on your laurels. Continue pursuing more opportunities to do more acts of righteousness. (Chozeh of Lublin)
13. It is a general rule that the Yetzer haRa seeks to mislead a person. The Yetzer haRa just does not only directly mislead a person to doing bad acts, G-d forbid, but at times the Yetzer haRa tells a person to be a Tzadik more than necessary. Thus, at times a person needs to “flee” from a being a Tzadik. (Rabbi Yechiel Michel from Tzlotshov).