Final answer:
The statement regarding the penalty for blocking after a fair-catch signal being 15 yards is true. In American football, this rule is in place to ensure player safety and prevent interference during a fair catch.
Step-by-step explanation:
The statement that the penalty for blocking after giving a valid or invalid fair-catch signal is 15 yards is generally true. In American football, fair catch signals are covered under specific regulations. When a player signals for a fair catch, they are signaling their intent to catch the ball without interference from the opposing team. Once they have made this signal, opposing players must allow them the opportunity to catch the ball without hindrance. If an opposing player blocks or tackles the player who has signaled for a fair catch, a 15-yard penalty for kick-catching interference is typically assessed.
The primary purpose of this rule is to ensure the safety of the player calling for the fair catch, as they are often in a vulnerable position while awaiting the ball. Any contact with a player who has made a fair-catch signal, whether it's considered valid or invalid, constitutes a violation of the rules. Therefore, the penalty serves as a deterrent for players to respect the fair catch signal and reduce the risk of injury on the field.