According to "Rookie Road," the NFL's blindside block rule is a rule that prevents defenders from blocking offensive players from their blindside.
A blindside block in the NFL occurs when a player blocks someone who is either looking away from them or in the direction away from the action of the play. Such a block could have dire consequences on the blocked player as they can lead to severe head injuries. As a result, the league eliminated blocks of that nature from the Gridiron in 2019.
According to Rule 12-2-7 of the NFL Rule Book, a blindside block occurs when a player initiates a block when his path is parallel to or towards his end line and makes gritty contact with his opponent with his forearm, shoulder or helmet,
Furthermore, it is essential to note that it is not a foul for a blindside block if the contact occurs in “close-line play” before the ball leaves the area. However, this exception does not apply to any action other than a designated play. That means that any forcible contact in “close-line play” remains subject to the restrictions for peelback and crackback blocks.
NFL owners voted to eliminate the dangerous blindside blocks in 2019. That happened at the annual league meetings for the 2019 season.
The league owners voted to eliminate blindside blocks ahead of the opening week and beyond, as, according to a report, about one-third of concussions were caused by said blindside blocks.
According to "Rookie Road," an illegal blindside block carries a penalty of 15 yards. It is important to note that 15 yards is the maximum distance for a penalty.
Furthermore, if such a blindside block is super aggressive, then the player could even be ejected from the rest of the game. That typically occurs when the contact of the block originated from the helmet.