Halakhah su Deuteronomio 16:21

And it appears that [also] included in this commandment is that anyone who the members of the community have chosen to appoint appointees over them for any matter, that they should put all of their attention and intellect [to it], to appoint those appropriate and good for that appointment that the community requires. And he should not be frightened from any man, to appoint someone that is not appropriate. And the Sages said (Avodah Zarah 52b, Sanhedrin 7b) about someone who sets up a judge that is not proper, [that it is] as if he puts up a stone pillar, as it is stated (Deuteronomy 16:22) [soon after the commandment to set up judges], "and you shall not set up a pillar for yourself." And if it is a place where there are Torah scholars in it, they said that it is like planting a tree-god, as it is stated (Deuteronomy 16:21), "You shall not plant a tree-god, any tree, beside the altar of the Lord, your God." And they also said (Sanhedrin 7b) that anyone who appoints a judge because of his wealth, about this is it stated (Shemot 20:20), "You shall not make with Me gods of silver and gods of gold." And they spoke at length about this matter and said (Talmud Yerushalmi Bikkurim 3:3) that it is forbidden to stand [for judgement] in front of a judge who gave money in order that he be appointed a judge. And they treated his honor very lightly, and said about him that the cloak with which he wraps himself should be like a donkey saddle in your eyes. And it was the way of the early Sages to flee from being appointed judges (Sanhedrin 14a), except in a place where there was no one greater than them.

To not plant any tree-idols: To not plant any trees in the Temple or next to the altar. And about this is it stated (Deuteronomy 17:21), "You shall not plant for yourself a tree-god, any tree next to the altar of the Lord, your God, etc." Rambam, may his memory be blessed, wrote about the reason for this prohibition (Sefer HaMitzvot LaRambam, Mitzvot Lo Taase 13) [that it is] since the worshippers of idolatry would do like this in their houses of idolatry to plant beautiful trees there. And [so] to distance anything that is similar to them from the thoughts of people that come to the worship of God, blessed be He, in the chosen place, we were prevented from planting any tree there. And from the angle of the simple understanding, [this explanation] is likely.