What is the definition of "Evyon"?
Rashi: "Evyon" refers to a person who is destitute 1 - he desires everything, because he has nothing.
As opposed to "Ani", which means 'a poor man'.
What are the ramifications of this prohibition?
Seforno: It is a prohibition against a. speaking softly to the wealthy litigant and harshly to the poor one, when they present their cases, and b. inviting the former to sit down, but not the latter.
Targum Onkelos and Targum Yonasan: It is a prohibition against perverting the judgment of a poor litigant.
See Torah Temimah, note 44.
Oznayim la'Torah, citing the Rambam in Hilchos Sanhedrin, 21:5: 'A Dayan may contend, neither with the past of the litigants (one is a Tzadik, the other, a Rasha), nor with their current situation (one is poor, the other, rich), nor with their roots (one is a Ger, the other, a native):
What are the implications of the word "be'Rivo"?
Yerushalmi Pe'ah, 4:5: You may not twist the Din in the poor man's favor in his disputes, but you may twist it in his favor regarding Leket, Shikchah and Pe'ah
Overriding the principle 'ha'Motzi me'Chavero, alav ha'Re'ayah.