NFL has strict rules to limit head injuries/BRAIN damage

THE NFL FOOTBALL SEASON JUST STARTED & NOW

THE NFL HAS NEW RULES DESIGNED TO LIMIT HEAD INJURIES

One of the new rules applies to all players in every position - A player many not launch himself off the ground to use his helmet to strike a player in a defenseless posture in the head or neck.  The old rule only applied to receivers getting hit.

“In the past, defensive players were allowed to hit receivers in the head once the receiver touched both feet on the ground.  Now, the officials will give the receiver more time to get into a defensive posture before the tackler is allowed to strike him.”(NFL.com New NFL Rules, 2012)

Also, now “when a player loses his helmet, the play is immediately whistled dead.  Further, during a field goal attempt, the defense cannot position a player directly across from the snapper, who's considered to be in a defenseless position.”( NFL.com New NFL Rules, 2012)

Now, when a player has suffered a concussion, they must consult with an independent neurologist before they may return to play.  

In summary, the NFL referees will penalize and/or fine a team/player more severely when a player hurts another player(s) who are in vulnerable positions because there is a real serious concern about the damage to the body that is done from big hits and what happens to the BRAIN.