Bluetooth phone call to 911 : "No, Truck driver is so close I'm afraid to slow down" , "I'm at the mile marker ___ " , "He keeps blowing his horn and charging the back of my Vehicle" , "HELP !"
or
From the road side , "Yes Officer , I got his tag number " , " Ya'll get him pulled over I'll follow along behind him and stop with ya'll to swear-out-the-warrant".
In some cases "snitching" someone out is really a public service.
Or , I do this one at least a couple times a year ,
follow them till they pull into a Police Station because they don't know what your going to do . If at night it helps to leave your bright beams on as much as possible .