Rule 3 – Section 5 – Article 2 – Legal Substitutions
A legal substitute may replace a player or fill a player vacancy provided none of the following restrictions are violated:
e. When Team A sends in its substitutes, the officials will not allow the ball to be snapped until Team B has been given an opportunity to substitute. While in the process of substitution or simulated substitution, Team A is prohibited from rushing quickly to the line of scrimmage with the obvious attempt of creating a defensive disadvantage. If the ball is ready for play, the game officials will not permit the ball to be snapped until Team B has placed substitutes in position and replaced players have left the field of play. Team B must react promptly with its substitutes.
PENALTY − [e] (First offence) Dead-ball foul. Delay of game on Team B for not completing its substitutions promptly, or delay of game on Team A for causing the play clock to expire. Five yards from the succeeding spot [S21: SUB]. The referee will then notify the head coach that any further use of this tactic will result in an unsportsmanlike conduct foul. (Second or more offence) Dead-ball foul, team unsportsmanlike conduct. An official will sound his whistle immediately. 15 yards from the succeeding spot. [S27: UC- UNS].