In 1980 the NFL created the rule that any strike to the face was considered a personal foul. This rule was created for player safety to allow less contact to the face, head and neck. There will be some instances where someone may grab an opposing players face mask or swing a forearm into the other players helmet, but this has been reprehended with a penalty that hurts your field position and possibly a fine.

In 1996 the NFL made a rule in which helmet to helmet contact was a personal foul. This rule was in favor of the quaterback who could be hit in the lineman's pocket with out knowing that someone was entering from behind. This rule has prevented many concussions as the hits to someones head has dropped in numbers since this rule has being enforced.

In 2005 the NFL implemented the rule that a defender was prohibited from hitting a passer in the knee or below unless they were blocked into the quarterback. This hit was implemented by Benard Pollard hitting Tom Brady and tearing his ACL.These rules would decrease the amount of ACL/MCL tears or any other knee injuries, saving the careers of many NFL players in the future. This rule may also prevent strained ankles or even broken ankles.

In 2010 the NFL banned Helmet to Helmet hits, they included a 15 yard penalty, a fine and a possible suspension not allowing a player to play a few games. This rule was created to try to eliminate possible concussions that may happen. In march of 2013 the NFL established a new safety rule that using the crown of your helmet for someone carrying the ball outside of the tackle box would be considered a penalty and would penalize your team 15 yards and possibly a fine this rule was created to also help with the current concussion problem in the NFL.

"Aaron Hernandez tackled by face mask" 

"Joe Webb tackled by face mask"

"Benard Pollard tackles Tom Brady in the knees"