Legal source, please.
my personal and business insurance agents
and
https://www.cantonrep.com/article/20130721/News/307219930
anything else google it.
I always get me legal advice from insurance people....
All I'll say is this: if I represented a person whose vehicle was damaged by rocks or whatever that fell off a truck and hit the ground first, I would not be too worried by this "defense" in Indiana, at least.