What is the horse collar tackle rule in high school?

The horse collar tackle rule in high school football prohibits a defensive player from tackling an opponent by grabbing the back of the shoulder pads and pulling the opponent downward to the ground. This rule is designed to reduce the risk of severe neck and head injuries. Any player who initiates a horse-collar tackle will be guilty of unnecessary roughness and subject to ejection from the game. Horse-collar tackles result in a 15-yard penalty. Tackling in such a manner could also cause ejections and suspensions by state associations or leagues.