This is an example of an offensive foul for illegally wiping away an opponent’s arm. Inside the Lower Defensive Box (the area from the bottom tip of free throw circle to the 3′ posted up marks), a post defender may legally place one hand, with a bent elbow, and/or one forearm onto the back of an offensive player with the ball and his back to the basket. Since the defender’s hand on this play is considered legal in this situation, the offensive player cannot simply knock that hand away. This is an offensive foul for the illegal wipe away motion.