The Ten Commandments are part of the OT Law, but NT authors do quote or allude to the commandments quite often as being relevant for new covenant Christians (except for one).
“The law says that every teacher, all public-school teachers, have to post the Ten Commandments in the front of their classroom, in a certain size font, and that they’re legally obligated to do this.
From displaying the Ten Commandments to demanding that teachers ... to blur the lines between church and state by infusing Christianity into public schools. And with Donald Trump headed back ...