When somebody cuts you off in traffic, don't start following the guy all over town, get the cops on the phone, and refuse to stop following the until a cop catches up to you and pulls the guy over. I can assure you, no cop is going to tear madly through the city to do a traffic stop on someone you say cut you off. In fact, the other guy is probably also calling the cops, reporting that some crazy bastard is chasing him all over town, screaming and gesturing at him, and he has no idea why. And in the end, you can't write him a ticket anyway because you're not a cop, and we can't write him one either because we weren't there when whatever really happened happened.