These verses are closely connected in subject with the following chapter, and introduce certain directions for the administration of justice and the carrying on of the civil government of the people in Canaan. During the lifetime of Moses, he himself, especially inspired and guided by God, was sufficient, with the aid of the subordinate judges (compare Exodus 18:13 ff), for the duties in question. But now that Moses was to be withdrawn, and the people would soon be scattered up and down the land of Canaan, regular and permanent provision must be made for civil and social order and good government.
Deuteronomy 16:21
A grove - Render, Thou shalt not plant for thee any tree as an idol: literally as an Asherah,” “i. e.” an image of Astarte or Ashtaroth, the Phoenician goddess (compare Deuteronomy 7:5 note, Deuteronomy 7:13 note). The word is rendered “grove” by the King James Version also in Deuteronomy 7:5; Deuteronomy 12:3; Exodus 34:13; Judges 6:25, but cannot be maintained, for the word is connected with various verbs which are quite inapplicable to a grove. The wooden idol in question was the stem of a tree, stripped of its boughs, set upright in the ground, and rudely carved with emblems.