Walter Camp was on the various collegiate football rules committees that developed the American game from his time as a player at Yale until his death. English rugby football rules at the time required a tackled player, when the ball was "fairly held," to put the ball down immediately for scrummage. Camp proposed at the U.S. College Football 1880 rules convention that the contested scrimmage be replaced with a "line of scrimmage" where the team with the ball started with uncontested possession. This change effectively created the evolution of the modern game of American football from its rugby football origins.
He is credited with innovations such as the snap-back from center, the system of downs, and the points system as well as the introduction of the now-standard offensive arrangement of players—a seven-man line and a four-man backfield consisting of a quarterback, two halfbacks, and a fullback. Camp was also responsible for introducing the "safety," the awarding of two points to the defensive side for tackling a ball carrier in his own end zone followed by a free kick by the offense from its own 20-yard line to restart play. This is significant as rugby union has no point value award for this action, but instead awards a scrum to the attacking side five meters from the goal line.