What, exactly, was the "Spring of Justice"?
Targum Onkelus: It is a location where the judges of that country would convene to dispense justice. 1
Rashi and Targum Yonasan: It is the very location at which Moshe and Aharon were destined to be punished, many years later (which then became known as "Mei Merivah"). 2
See also Ramban, refer to 14:7:1.2:2.
In the same vein, Rashi points out that the Pasuk refers here to one of the areas that the four kings defeated as "the Field of Amalek," even though Amalek was not even born yet. See Ramban.
QUESTIONS ON RASHI
Rashi writes: "Ein Mishpat, which is Kadesh - so called because Moshe and Aharon would later be judged there; this is Mei Merivah." Ramban asks - This is not the same Kadesh! Moshe and Aharon were judged in Kadesh, Midbar Tzin, in the 40th year in the desert. The Kadesh of our verse (near Paran), must be Kadesh-Barnea, Midbar Paran, from which the Meraglim were sent in the second year in the desert!
Gur Aryeh: Midbar Kadesh is the general name for as vast area of desert, which included both Midbar Paran and Midbar Tzin, as well as a specific place called Kadesh-Barnea. 1
Gur Aryeh: The thirty-eight years wandering in the desert were spent half within Midbar Kadesh, and half wandering in its vicinity and then returning to Kadesh (Rashi to Devarim 1:46, based on Seder Olam). Therefore, they were still there in the 40th year. See also Tosfos to Shabbos 89a DH Midbar.
Rashi writes: "But Onkelus interprets 'Ein Mishpat' literally - the place where the local citizens would gather for judgment." Onkelus writes, "Meishar Pilug Dina;" what does this mean, and how does it emerge from the Pasuk?
Gur Aryeh #1: "Pilug Dina" means "the splitting of judgment" between the exonerated and guilty parties. We interpret "Ein Mishpat" as, "l'Ayein b'Mishpat," "to look [thoroughly] into judgment."
Gur Aryeh #2 (citing Ramban): "Pilug Dina" means "the depth of judgment," as in, "getting to the depths of the matter." "Ein Mishpat" is an analogy to a spring that emerges from the deep.
Rashi writes: "The fields of the Amalekim - Amalek had not yet been born; the Torah calls the location by its future name." Ramban asks - Moshe Rabeinu wrote the name as it was called in his day; if so, this is not a future name?