Now he knows

I was with a cluster of vehicles driving just a hair over the speed limit. One after another, drivers would zoom past on the left, only to slow down because the way was blocked by us slower vehicles.

One impatient guy pulled into the HOV lane even though he was alone. A couple of seconds later he swerved quickly back into his previous lane because he saw what the rest of us already knew. There was a State Trooper at the head of the pack.