Legal guarding position?
 

Player A1 has the ball and is dribbling towards his basket on a fast break. Player B1 is in front of A1 and is running down to meet A1 at the rim. Player B1 never establishes LGP. As they approach the rim, B1 is defending with his arms vertical, and his back is to A1. A1 initiates contact with B1 by lowering his shoulder to create space for a layup, and barrels through B1. My partner calls a PC foul on A1.

I thought it was a block because the defender never established LGP, regardless of if the offensive player initiated contact. What is the correct ruling for this situation?

PC, when two players are running in the same path, the one behind is responsible for contact. LGP not required.

PC foul all way if A1 displaced B1. B1 did not cause contact and is not responsible. LGP is there to protect the defender when contact occurs. But that does not give the offensive player to push off a defender from their movement because they have the ball.

Peace

Would you say that when a defender is in LGP, he/she never initiates contact?

No.

I asked the question really badly. I'm thinking that when a player has LGP, there is very little he can do to foul someone without losing LGP. This is why "refereeing the defense" is so important, right?

A player may make movements that don't cost him LGP but are not protected by LGP.

Like what?

Given that LGP is only relevant to block/charge, I believe that any movement that makes it a block is so because it made them lose LGP.