I think it's very important to call the police when you see something wrong- especially a drunk driver. Even if the driver wasn't drunk something was wrong for him to be driving so poorly.

It actually surprises me how many people turn their heads the other way and don't do anything. Once while driving down a busy highway Justin and I saw a car on the side of the road completely engulfed in flames, we called 911 and they had no idea about the car, no one had yet reported it. Justin and I pulled into a gas station nearby and waited until we saw the fire trucks arrive. I've also called (a non-emergency number) twice to report loose cows walking in the road. Both times they were on semi-busy roads, but thankfully not highways.