Is it true that a substitute entering the field without permission cannot be sent off if they interfere with play?

The statement is false. According to the Laws of the Game, if a substitute enters the field without permission and interferes with play, the referee has the authority to take action against that substitute. Specifically, if a substitute enters the field of play improperly and commits an offense or interferes with play, the referee can issue a caution (yellow card) or send the player off (red card) depending on the severity of the interference. This can include situations where the substitute actively engages in play or affects the gameplay in any significant way.

The referee's responsibility is to maintain control of the match, and allowing a substitute to enter without permission disrupts that control. Consequently, referees are empowered to enforce rules that maintain the integrity and safety of the game by taking appropriate action against unauthorized substitutions.

Understanding this highlights the importance of proper procedure regarding substitutions in soccer and the authority referees have to ensure that all players, including substitutes, adhere to the rules of the game.