The final, and arguably most critical innovation, which might finally make American football uniquely "American", was the legalization of interference, or blocking, a tactic which was remarkably illegal beneath the rugby-style policies. Interference continues to be strictly illegal in both equally rugby codes. The prohibition of interference within the rugby match stems from the sport's stringent enforcement of its offside rule, which prohibited any participant on the crew with possession of your ball to loiter in between the ball plus the goal. In the beginning, American gamers would find Imaginative means of aiding the runner by pretending to unintentionally knock into defenders attempting to deal with the runner.

The back again choose is positioned deep during the defensive backfield, powering the umpire. The back again decide makes certain that the defensive workforce has no more than 11 players site on the sector and decides irrespective of whether catches are legal, whether or not discipline purpose or more issue attempts are good, and regardless of whether a move interference violation transpired.