My insurance company sent me a form hoping that my sprained wrist might be the fault of someone they can sue rather than just pay my claim, and on the check list is an entry for 'other vehicle' where they list a lot of possibilities (motorcycle, bus, boat, jetski, snowmobile, 'other'). If I check 'other' (for bike) there's another 3 pages to fill out about possible other insurance policies that might be responsible instead of my health insurance, all specifying identification of an at-fault party.
I didn't check any of the other things and avoided all those other pages, and basically denied that anyone was at fault but myself, although I didn't say it was my fault either, I don't like the legalistic sound of 'at fault party' here. Hey, accidents happen. They might still call me back to see if they can sue the city for leaving leaves on the bike trail but I will cross that bridge when I get to it.