Albert Barnes Commentary Deuteronomy 12:1

"These are the statutes and the ordinances which ye shall observe to do in the land which Jehovah, the God of thy fathers, hath given thee to possess it, all the days that ye live upon the earth." — Deuteronomy 12:1 (ASV)

In Deuteronomy 12–26, Moses now proceeds to apply the leading principles of the Decalogue to the ecclesiastical, civil, and social life of the people. Details unique to the Law as given in Deuteronomy will be noted; and even in laws repeated from the earlier books, various new circumstances and details are introduced.

This is only natural. The Sinaitic legislation was nearly 40 years old and had been given under conditions of time, place, and circumstance different from, and distant from, those now present. Yet the Sinaitic system, far from being set aside or in any way abrogated, is, on the contrary, presupposed and assumed throughout. Its existence and authority are taken as the starting-point for what is prescribed here, and an accurate acquaintance with it on the part of the people is taken for granted.