Speed Trap Reversal

I've lived in several places in which the local government likes to place very low speed limit signs at the base of very steep hills, then hide police cars in hidden spots just past the signs, off the road in places where no other vehicle could legally go, such as behind bushes or in ditches that are craftily placed in grassy islands between lanes, so they're not visible to oncoming drivers. In many such places, it is technically illegal for them to do so, and if you know this and can prove that they weren't visible, you can beat the ticket in court. Even then, the ticket just gets thrown out and the officer who broke the law gets off Scot-free. But why should we, the People, have to go to such lengths to hold our police officers accountable?

I say that a team of secretive vigilantes should identify the favorite hide-outs used for speed traps, which can easily be found in some areas with a neat iPhone app called Trapster, and set traps for the would-be entrappers, such as sand pits, or caltrops. Take away their illegal edge.