Here is the list of Defenseless Players. The list was expanded in 2013-14 to prevent "cheap shots" in certain situations. Be careful with 7, I've seen many instances of these blocks real close to being targeting fouls.
1. Passer
2. Receiver of pass
3. Kicker
4. Kick returner
5. Player on the ground (includes holder)
6. Player obviously out of the play
7. Player who receives blind-side block
8. Ball carrier in grasp of defenders & forward progress stopped
9. QB after change of possession
