Flag football follows the majority of the same rules that regular American football does, except that flag removal replaces tackling. The ball is marked down at the point where the clip of the flag belt becomes detached, not where the belt falls to the ground.
The balled is also ruled dead when the ball carrier touches the ground with any part of their body other than the hands or feet or when a fumble hits the ground. Fumbles occur when player drops the ball within the field of play or when a snap from the center touches the ground. Every member of the offense (even the center) is allowed to catch a pass, unless the player voluntarily leaves the field of the play while the ball is live. Every member of the offense must come to a full stop for at least one second prior to the snap, and only one player is allowed in motion prior to the snap.
The defense must line up at least one yard off the line of scrimmage, even if the ball is placed within one yard of the goal line. Defensive players are allowed to leave their feet in pursuit of an opponent's flag, but tripping and contacting an opponent who is already on the ground is illegal.