I forget the kind of car it was on, but it was a white bumper sticker with a cartoon drawing of an ambulance and the following text, in a handwriting-ish font:
My son saved a life today
. . . what did yours do?
Boggling over the awfulness was at least a nice distraction for the rest of the walk from my parking lot (I was annoyed at myself for leaving my purse at the grocery store and losing a half-hour I couldn't afford as a result).
Right, back to legal research.