It's a secondary offence here (meaning they have to pull you over for something else, like speeding). Our aggressive driver hotline is a waste. I've called twice (once driving, when a neighbour I'd been in a tiff with attempted to run me into a highway divider; once cycling when a driver kept swooping into the bike lane as we leapfrogged each other in a traffic backup) and neither time was there any response. I've been told "we'll send an officer that way, but unless the officer sees it happen, there's nothing we can do."

Which, to me, is the same as saying "just screw with them right back, as long as a cop doesn't catch you."