Originally posted by 49ersalldaway126:
block in the back is a block in the back its a saftey rule (whiplash)
Wrong, there are exceptions to blocking in the back:
(taking from my NCAA Rule Book I'm pretty sure the rule is the same in the NFL) Offensive playes who are on the line of scrimmage at the snap within the blocking zone (Rule 2-3-6) may legally block in the back in the blocking zone, subject to the following restrictions:
A. A player on the line of scrimmage within this blocking zone may not leave the zone and return and legally block in the back.
B. The blocking zone disintegrates when hte ball leaves the zone.
Blocking zone: is a rectangle centered on the middle lineman of the offensive formation and extending five yards laterally and three yards longitudeinally in each direction.