"crackback block"

[NJ Official]

Originally Posted by JRutledge

There is no foul for a defenseless player unless they are out of the play. If they are actively trying to play football, they are able to be blocked, even with force. At least that is what we were told by our state's interpretation.

Peace

It may be different state to state but what you mentioned is what we have always done, if they take a unnecessary shot away from the ball it gets called. The new definition of a defenseless player: A defenseless player is a player who, because of his physical position and focus of concentration, is especially vulnerable to injury.

By definition it seems crackback blocks would be a foul, but I guess it might vary state to state on how it is interpreted.