C. F. Keil and Franz Delitzsch on 2 Samuel 15:4

2Sa 15:4

Absalom also said, “Oh that I might be judge in the land, and every one who had a cause might come before me; I would procure him justice!” ישׂמני מי is a wish: “who might (i.e., oh that one might) appoint me judge,” an analogous expression to יתּן ot מי (vid., Gesenius, §136, 1, and Ewald, §329, c.). עלי placed before יבא for the sake of emphasis, may be explained from the fact that a judge sat, so that the person who stood before him rose above him (comp. Exo 18:13 with Gen 18:8). הצדּיק, to speak justly, or help to justice.