[Rich]

Originally Posted by Robert Goodman

No, it was supposed to be to protect the knees, as was explained first to me here. If you're collared while running forward, your head will snap forward, not backward. It could bounce backward, of course, but the neck is not what this rule is about. If it were about protecting the neck, then all neck tackling would be outlawed, regardless of direction. And if it were about whiplash, then tackling from behind via contact with the back would be forbidden.

Right, it protects the legs. That, from everything I heard, was the main intent of the rule.