I've never used these. I drive like a grandpa in the street. But one of my friends that has a laser jammer has his hooked on to a switch.
He does this so the jammer is always jamming, but if his radar goes off he will slow down and once he is at the speed limit he turns off the jammer. That way the police catch you going speed limit.
Pretty genius in my opinion, especially in states where they are illegal.