Clarence Busch, a man with multiple arrests for intoxication including a hit-and-run drunk-driving charge from less than a week earlier, killed 13-year-old Cari Lightner on a quiet road in Fair Oaks, California, on 3 May 1980. In response, Cari's mother Candace founded MADD: Mothers Against Drunk Driving, which in just four years got the Federal Government and most of the states to crack down on drunk driving. The organization and the legislation they got passed reduced drunk-driving deaths 40% by 2000.
My dad met Candy Lightner in 1982, and wrote an Emmy-nominated TV movie about her and her success in saving other people from drunk drivers, for which he received a Writers Guild award in 1984. (He would have won the Emmy for Outstanding Drama Special as well but for the truly groundbreaking Special Bulletin.)
You can watch the trailer for MADD on Video Detective, and the entire movie Special Bulletin on YouTube.