defender's shoulders to get the rebound. If you can't reach basically straight up to get the ball, you don't have position for the rebound, IMO. The defender has the right to make contact during a box out, that's why coaches teach their players to do so. If everyone on the team boxes out and clears out the space around the rim, almost the only way the offense can get the rebound legally is if the ball goes over the head of all of the defenders. It's beautiful when done correctly. That said, you can definitely foul on a box out by reaching your hands back to "trap" the defender behind you.