yeah, it's always a judgement call for sure. in my case it was obviously deliberate because I could see his eyes in his mirrors the whole time and both hands were on the wheel, he was in complete control of his vehicle. he thought I should either be off the road or in the gutter. he did not want to share the road. he wanted to threaten me. he invited a confrontation / conversation. when I am all jacked up on adrenaline, caffeine and simple carbs you don't want to threaten my life. in the fight or flight scenario I will react. in my case he was a sitting duck trapped in traffic in front of our police station. he was a nerd who felt anonymous and protected and privileged. I believe in that case I made the right choice. it's rare to catch up to a driver like that. it's rare to see their eyes so clearly. it's rare that a threatening driver is a geek. usually they are young males in mustangs, jeeps or pickups. if windows are smoked out you have to decide if you want to have the possibility of someone losing it, leaving their vehicle, perhaps with a weapon, or chasing you with their vehicle. also are there witnesses present, etc. I'm 54 and been in enough confrontations to know when to hold'm and when to show'm if you know what I mean. my urban high school was the best learning experience for most of that.