There was a news clip on BBC of all places showing a CHP Motor Cop demoing a new hand held laser which read out both speed and distance times between oncoming vehicles. He was shown giving a ticket to a fellow doing 57 in a 55mph zone but had only a .73 of a second distance to the car infront of him. He told the guy he had to give 3 seconds or get tagged.
I think I could live with this type of enforcement. I really hate guys coming up behind me and sitting on my bumper.