There are specific rules governing conduct in the offensive backfield. There are many rules which differ for play in the offensive backfield as opposed to play in front of the line of scrimmage. The
1906 football rule reforms mandated that the offensive team line up with at least seven players on the line of scrimmage, which are now commonly called "linemen". Therefore, a maximum of four players are allowed in the offensive backfield. The other players not on the line of scrimmage may be positioned anywhere, but all must be at least 1 yard behind the seven or more players on the line of scrimmage. A
forward pass can only be legally made from the offensive backfield. There are also rules. If the pass is not deemed a forward pass, and is not caught the ball is still considered live and can be picked up by either team. Over time, these rules have been changed to account for the evolving nature of the game. The tuck rule was an especially controversial rule that stated any forward motion of the quarterback's arm results in an attempted forward pass. Thus, if the ball were to drop to the ground, it would be ruled an incompletion instead of fumble. The quarterback can run as far back as he wants with the ball, but if he is still inside the "
tacklebox" (the area between where the tackles line up) and does not throw the ball past the line of scrimmage, he will be called with intentional grounding which results in a 10-yard penalty and a loss of the down. There is no intentional grounding for the ball not crossing the line of scrimmage if the quarterback was outside of the tackle box when the ball was thrown. ==References==