The first specific example of this emphasis had to do with any case of an unsolved murder. Whichever Israelite city was closest to the scene of the crime was held responsible for it. So, there had to be a special sacrifice made to purge them of the guilt of the shed blood... even though they had no knowledge of it. This, of course, meant that local leaders were required to see that a reasonable measure of policing was done within their jurisdiction.
Additionally, Deuteronomy 21:10-14 applied to the rights of female captives who were taken in war. Deuteronomy 21:15-17 is NOT meant to be an endorsement of polygamy. Actually, it is a regulation that required men in that situation to treat their children equally and without favoritism regardless of which wife was their mother. Deuteronomy 21:18-21 gave parents who had rebellious and unruly children a strong recourse if they couldn't manage their own kids. So important to Him is this matter that He ordained capital punishment for any son who couldn't be controlled.