a question for you rules gurus

I have bagged on last nights refs ... that is NOT what this question is about, i am looking for a better understanding.



The play that hurt Williams was a tackle in which it appeared that the defender collided, helmet to helmet, with Jamaal. Is that type of collission technically a violation or are the rules worded differently so that thisvcould wouldnt even technically be included?



I'm looking for a better understanding of the rules re leading with your helmet and helmet to helmet contact.

I believe it is an outside the tackle rule. Running between the tackles provides no protection from the new rules.