The team bench area shall be a rectangular area situated not closer to the Sideline than 6 feet and extending for a distance of 30 yards parallel to the Sideline. During a game, the area may be occupied only by substitute players in uniform and other accredited persons including coaches, doctors, trainers, equipment assistants and water carriers. All such personnel are required to remain within the rectangular area with the exception of the coaches, who may take positions between the bench area and the Sideline. The coaches shall not be permitted on the playing field at any time during the game, except with the permission of the Referee.
When the Referee has called an official time out, not more than one player of each team may proceed to the Sideline to talk with the coach.
During a stoppage in play for injury or other reason, not more than two representatives of each team, other than medical personnel, shall be allowed to enter the field.
The Referee need not permit the attendants of both teams to enter the field in case of injury to a player of one team only and shall indicate such permission to the attendants of one or both teams.
When time out has been called for player injury or equipment repair, that player shall be required to leave the game for a minimum of three plays, except when the injury had occurred as a result of an infraction for which the opponent was penalized.
A substitute may enter the Field of Play at any time the ball is dead and only at that time.
A substitute who enters the game and communicates with a team mate on the field must remain in the game for at least one play.
A player leaving the game shall proceed directly to the Sideline on which the team bench is located and, thence, outside the Field of Play to the team bench. A team shall not be permitted to use player substitution as a means of deceiving the opponents.
A team that permits more than 12 players to participate in its huddle or formation before the ball is snapped shall be subject to a penalty for illegal substitution.
The Head Linesman (HL) and Line Judge (LJ) shall monitor the team bench on their sides of the field and, when the ball becomes dead, shall observe that Sideline for possible substitutions. If Team A substitutes players, the Referee shall give Team B the opportunity to also substitute players prior to starting the Play Clock. When Team A breaks their huddle the HL and LJ shall turn away from the Sidelines and raise their arms to shoulder level (raise the “gates”). If Team A does not huddle, once the Referee signals the Umpire to leave the football, the “gates” will go up. Further substitution by Team A shall not be permitted once the “gates” are raised. Team B shall be permitted in all situations including after the “gates” have gone up, to substitute up to the snap of the ball.
When, on a kicking play, Team A has only 11 players on the field and the "gates" have gone up, a player may enter the field and participate in the play without being penalized for Illegal Substitution, if he is able to enter the "Close Line Play Area" and then assume a position, inside or outside this area, prior to the snap.
A sleeper play is one in which Team A uses substitution procedures to disguise a player's presence on the field and eligibility as a potential pass receiver, and throws a pass to that player.
Team A shall not use player substitution as a means of disguising a sleeper play. If following a substitution, a Team A player does not participate in the team huddle and takes a position within 11 yards of the Sideline adjacent to the Team A bench area when the ball is put into play, that player shall be deemed to be ineligible as a pass receiver.
If through error in substitution or otherwise, a team has more than 12 players on the field, the offending team shall be penalized.