Helmet-to-helmet collisions are occurrences in American football when two players' helmets make head-to-head contact with a high degree of force. Despite its long association with the sport, this type of contact is now considered to be dangerous play by league authorities due to the potential of causing serious injury. Major football leagues, such as the NFL and NCAA, have taken a tougher stance on helmet-to-helmet collisions after the US Congress launched an investigation into the effects repeated concussions have on football players. Other possible injuries include head traumas, spinal cord injuries, and even death; nevertheless helmet manufacturers are constantly improving their designs in order to best protect their users against injuries from such collisions. Intentionally causing a helmet-to-helmet collision is banned in most, if not all, football leagues.
The crack down on helmet-to-helmet collisions has resulted in reappraisals of the sport. An image of two helmets smashing together - which had been a staple for 20 years - was dropped in 2006 from Monday Night Football on ESPN. The NFL also ordered Toyota Motor Company to stop using similar helmet collision in its advertisements.
However despite the safety concerns, some professional football players have criticized bans on helmet-to-helmet collisions on the basis that gridiron football is a game that is supposed to be composed of the world's biggest and best athletes, and placing such restrictions "waters down" the game.
Rules by league
- Helmet-to-helmet hits are banned in the NFL, with a penalty of 15 yards for violations. In 2010, the NFL placed its policies pertaining to these incidents under review, considering heavy fines and suspensions. In addition to prohibiting these hits during actual play, the NFL does not allow the sale of these hits on its site in hopes of reducing them.
- The Canadian Football League prohibits the use of the helmet to butt, ram, or spear an opponent. Players are penalized for what is not deemed to be an 'acceptable' football play.
- In the NCAA, helmet-to-helmet collisions have been banned for years, but they were illegal only when intentional. In 2005, the NCAA took the word "intentional" out of the rules in hopes of reducing these incidents even further.
Notable helmet-to-helmet collisions
- Former Carolina Panthers running back Eric Shelton sued the NFL in 2010, alleging that a helmet-to-helmet collision caused him a spinal cord injury that left him paralyzed, and he was not appropriately compensated for his injuries.
- In 2011, a Frostburg State player died from a helmet-to-helmet collision.
- On October 17, 2011, a 16-year-old high school football player in Homer, New York died from bleeding in the brain suffered from a helmet-to-helmet collision. 
- On December 13, 2011, the NFL suspended Steelers linebacker James Harrison for one game for a helmet-to-helmet hit that caused Browns quarterback Colt McCoy to suffer a concussion. It was the first time the NFL ever suspended anyone for this violation. NFL commissioner Roger Goodell said he chose to suspend Harrison because it was his fifth such hit in three years. The suspension cost Harrison $215,000 in salary.
- Gill, Sam (October 27, 2010). "Helmet-to-helmet hypocrisy: NFL, NCAA blame football players - when the problem is football programs". New York Daily News (in English). Retrieved 13 December 2011.
- Garrett, Melanie. Under His Helmet: A Football Devotional. p. 23.
- Thomas, Katie (October 21, 2010). "N.F.L.’s Policy on Helmet-to-Helmet Hits Makes Highlights Distasteful". New York Times (in English). Retrieved 9 December 2011.
- Gregory, Sean (Oct. 22, 2010). "Can Football Finally Tackle Its Injury Problem?" (in English). Time Magazine. Retrieved 13 December 2011.
- Bucholtz, Andrew. "Concussions: the CFL's rules and the impact on defensive players" (in English). Yahoo Sports. Retrieved 27 December 2011.
- Nowinski, Christopher. Head games: football's concussion crisis from the NFL to youth leagues. pp. 104–05.
- Schwartz, Allan (November 29, 2010). "Ex-Player Is Suing Over Pay for Injury". New York Times (in English). Retrieved 12 December 2011.
- Quigley, Rachel (September 15, 2011). "Another young footballer dies from brain injury after helmet-to-helmet collision". MailOnlineNews (in English) (CBS news). Retrieved 12 December 2011.
- Eliasoph, Jeff (October 17, 2011). "16 year old football player killed by helmet to helmet contact" (in English). KWWL News. Retrieved 13 December 2011.
- Klemko, Robert (Dec 13, 2011). "Steelers LB James Harrison suspended one game". USA Today (in English). Retrieved 13 December 2011.