Euphoria

Ok here is where I think its confusing everyone...

-Chop block is the one that is below the waist.

-Crackback Block is where you have a Defensive player going in one direction pursuant to the ball carrier and an offensive player is usually wide and lays that defender as if sealing the edge and the defender has no idea its coming. Its a way of protecting the defender... This was started back when Warren Sapp laid out a punter many years ago. They have been calling this penalty in a lot of games and its consistent with other games. I recall seeing one in a Giants game not that long ago.
you can hold him up and you can get in his way but you can't deck him because he is a defenseless player in a way.

E U P H O R I A

hitta

A crackback block is not illegal. A high or low crackback block is. The crackback block was made into a defenseless position around 2012. Yes he is in a defenseless position, but for it to be an illegal hit has to be high or low. Just hitting a player in defenseless position is never really illegal. Leading with the crown of the helmet, going helmet to helmet, or going below the waist is.

A chop block is a scissors block where one player goes high and one player goes low. The penalty is usually called on the second player to engage.

Chop blocks most of the time occur by the offensive lineman. There is actually a lot of helmet to helmet contact that occurs on the line, and isn't illegal. Helmet to helmet isn't always illegal, just on players in defenseless positions. Chopblocks have nothing to do with defenseless position, it's just when someone goes high and someone else goes low simultaneously.