gps-4

[crew]

nc2a 4-4.8.7
b1 is standing standing directly under the basket before a1 jumps for the layup. the forward momentum of airborn shooter a1 causes a1 to run into b1. RULING: b1 is not in legal guarding position. blocking foul on b1. (women)

though this is for the womens game it is taught at mens camps as well. it is good practice to call this a defensive foul. though you do not have to call the game as i do.