Why does it say "Melech b'Mishpat Ya'amid Aretz"?
Rashi citing Sanhedrin 7b: If a judge is like a king, who does not need anyone else 1 , he will establish order in the land. Rashi - he need not acquire lovers and take bribes.
Rashi: If he judges Emes, he stands up the land.
Malbim: The king and Kohen Gadol erect the bases of Mishpat and Tzedakah. The king erects the base of Mishpat Bein Adam l'Chavero. The Kohen Gadol is appointed over Beis Elokim and Avodas Hashem, and ruling in Torah and Mitzvos to stand up Tzedakah, i.e. Mitzvos Bein Adam la'Makom. When both of them go in Derech Hashem, they stand up the land.
R. Chananel (7b): He is financially independent. Rashi (7b) - he is expert in the laws.
Why does it say "v'Ish Terumos Yehersenah"?
Rashi citing Sanhedrin 7b: If a judge is like a Kohen who goes to the granaries to ask for Terumah 1 , he will destroy the land.
Rashi: He is haughty. He is not concerned to be deliberate in judgment.
Malbim: If the Kohen Gadol and the Kohanim under him do not engage to straighten the nation, only to receive Terumah and Ma'aser, they destroy what the king built (standing up the land via Mishpat). Without Avodas Hashem, Emunah and Tzedakah, also Mishpat is not founded - "Hago Rasha Lifnei Melech v'Yikon b'Tzedek Kis'o" (25:5).
R. Chananel (7b): He cannot protest against those on whom he is financially dependent. Rashi (7b) - he needs to ask Beis Din (for he is not expert in the laws).
