Charles Ellicott Commentary Judges 17:6

"In those days there was no king in Israel: every man did that which was right in his own eyes." — Judges 17:6 (ASV)

In those days there was no king. —This shows that these narratives were written, or more probably edited, in the days of the monarchy. (Judges 19:1; Judges 21:25.)

Did that which was right in his own eyes. —The notice is added to show why there was no authoritative interference of prince or ruler to prevent idolatrous or lawless proceedings. (Deuteronomy 12:8: Ye shall not do after all the things which we do here this day, every man what is right in his own eyes.)