Every player is entitled to a spot on the playing court
 

I think it's rule 4-23-1--"Every player is entitled to a spot on the playing court provided such player gets there first without illegally contacting an opponent." Does that mean that a defender can place his body and legally establish his position in the path of a moving offensive opponent right before contact occurs without ever having to face the opponent and establishing LGP?

The defender hasn't established legal guarding position, but that just gives the defneder additional rights.

So, what part of 4-guarding or 4-screening did the defender violate? (it might be none, and it might depend on whether the offensive player has the ball)

He can if the opponent has the ball. No time and distance requirements.

If the opponent doesn't have the ball, the time and distance applies.

Ok. What if: B2 is facing away from dribbler A1. At the last second, B2 places his body in the path of moving dribbler A1, and never had his torso faced A1. Is B2 entitled to his new spot?

Yes they are. Just because you are not in LGP does not mean you do not have the right to your position on the floor. All LGP does is give the defense some options to keep in front of the a ball handler and move to maintain a legal position. But if I got to a spot first and did not move towards that ball handler, I am still able to hold my position legally.

Peace

Not sure I exactly agree with that....if the person is not in LGP, any movement, even lateral movement, is illegal if there is contact.

If you're not in LGP, you MUST be either stationary or moving directly AWAY from the opponent....lateral movement can only lead to a block if there is contact.

So, in the case that was presented, I'm probably calling a block unless the player got to the position and CLEARLY became stationary before any contact occurred. As it was presented, it sounds to me like the defender may have made it into the spot first but was probably still moving...and guilty of a block. Just getting the body in their path is not sufficient, otherwise, LGP would never be relevant.

I am not sure what you disagree with.

Well according to the S&I book on page 91, there is a shooter that is an airborne and runs into a defender with their back to the play near the basket. According to the book, the defender has a "legal position" and a PC foul should be properly called. The example says nothing about getting the defender gaining LGP first, just that they were standing there. Now if that player moves then we can have a different conversation and then we will likely agree totally. But if all the defender does was stand there, or starts going away from the ball handler, I do not see anything illegal on the defender's in the situation we are talking about.

Peace

That player in the S&I is implied to have been in that spot and is stationary. The timing of getting to that spot matters. The defender can't just arrive that that spot the instant before the shooter jumps....that would require LGP and they don't have that. That is the play being proposed by MiamiWadeCounty.

Now what I think you're adding to this is that the shooter is entitled to complete the shooting motion and land. That's a different dynamic. I agree with J-Rut. Everybody has a right to their spot on the court, but LGP gives additional rights.

No, if a defender crosses into a spot in the path of a shooter/dribbler with their back to the offensive player...i'm calling a block unless they get there AND stop clearly before contact. Otherwise, I'm considering them to be moving and not in a legal position.

A shooter is not entitled to "complete the shooting motion and land" if a defender gets to his spot first legally. If what you said was true, then all plays to the basket would be automatic blocking fouls.

Yes, that's the play I was trying to proposed. Another thread, someone said that you treat the defender as a screener and apply screening rules. Is this person correct?