A helmet to helmet hit is when a player uses his helmet to strike an opposing player in the helmet. Due to the severe nature of the injuries that can occur as a result of this type of hit, helmet to helmet hits are penalties in the NFL, whether incidental or deliberate. Defensively, helmet to helmet penalties are usually flagged during the process of making a tackle. However, the penalty can also be enforced on an offensive player making a block or a defensive player making a block after a turnover.
At minimum, a helmet to helmet hit results in a 15-yard penalty. In terms of severity, 15 yards is the largest ball-movement penalty issued by the NFL. However, in 2007, the NFL encouraged referees to eject any player deemed to have flagrantly committed a helmet to helmet violation. Special emphasis was placed on players in defenseless positions, making them the most vulnerable to serious injury. It is worth noting that contact between helmets alone does not mandate a penalty. Often times helmets clash after shoulder pads collide. These collisions are expected and remain part of the violent nature of the game. Instead, the penalties in place are meant to prohibit contact initiated with helmets.
In 1996, the NFL instituted a rule change that prohibited hits initiated by the defender with his helmet or targeted at the head of an offensive player. The penalty was classified as personal foul misconduct and resulted in both a 15-yard penalty and subsequent fines from the NFL. In 2002, the NFL implemented an addendum to the helmet to helmet rule, making it illegal to hit a quarterback helmet to helmet after a turnover. In 2009, penalties for blockers were instituted. Any contact with the helmet or neck of an opponent made during a blind-side block, whether by helmet, forearm or shoulder, would result in a 15-yard personal foul penalty.