Musar על סנהדרין 14:26

ולא יזח החושן מעל האפוד. Rabbi Menachem Ha-Bavli writes about this verse that the reason for this commandment is analogous to the principle that anyone who appoints a judge who is unworthy of the position is as though he had built an אשרה, a grove for idol worship (Sanhedrin 7). The Choshen is an instrument to obtain forgiveness for the sin of perverted justice, whereas the ephod is meant to obtain forgiveness for the sin of idol worship. We know this from Hoseah 3,4 who describes the absence of properly constituted authority in Israel in the same breath as he bemoans the absence of ephod and teraphim. Such absence was due to the sin of idol worship committed by Israel. The חושן, breastplate, was permanently attached to the ephod in order to discipline the sinners who passed by, since the Torah legislates that people have to be reminded by hearing about public execution for this crime in order that they should become afraid (Deut. 13,12 et al). We have a principle that if an object must be destroyed for legal reasons, then even if it still exists in an undamaged form it is legally considered as having been destroyed and must not be used for the pupose it had once been designed (Chullin 89). Being afraid of the penalty of idol worship has the desired effect. The exposure to the sight of the High Priest wearing the ephod on his back and the חושן in front over his heart, there would be a constant reminder of this warning to all who saw the High Priest.

The fifth category is a man who is trustworthy in the eyes of all the people, and to whom everybody listens, and who appoints his relative as synagogue warden or as Rabbi, saying, "I have appointed him because he is wise," when the fact of the matter is not so, all the people rely upon him. And the same is true of one who says about someone whom he does not know that he is trustworthy, with the result that the people put their pledges into his hand and he deceives them, and the Sages, of blessed memory, said : "Anyone who sets up a judge that is not worthy, it is as though he planted an idolatrous grove in Israel, and if he did so in a place where there are scholars, then it is as though he had planted this pagan grove near the altar itself. And the Holy One, Blessed be He, will surely exact retribution in the future from those who set up this type of judge" (Sanh. 7b).

The examples of אשרה and מצבה are selected as representing something totally blemished. The Canaanites used to engrave likenesses of their deities on stones or trees. These images would grow with the tree. The Canaanites would worship those trees and prostrate themselves before them. Our sages made a very apt comparison between the unfit judge with ever-increasing authority and the אשרה which does not produce fruit. Rabbi Menachem Habavli calculated that the numerical value of the word אשרה and the word דיין is an identical 11, provided we use the system known as מספר קטן which ignores all the zeros (wherever they may be). The numerical value of the word מצבה, adding the digit 1 for the word itself and also using the מספר קטן method, is the same as that of the word פרנס=21. It follows then that an אשרה is equivalent to a dried out tree unable even to provide shade. Leaders unfit for their position are compared to the מצבה, a stone, totally devoid of all feelings.