Defensive players legally may contact opponents who have crossed the neutral zone if the opponents are not in a position to receive a catchable forward pass.
What should we understand as "in a position to receive a catchable forward pass"? Is this a receiver turned to the QB, expecting the ball?
Or also a receiver running in a spot to which the QB might just throw the ball, and the receiver might just catch it if he is going to look back just in time? A receiver running a curl (4) route for example.
If we also interpret the second example as "in a position to receive a catchable forward pass", where do we draw the line? What would then constitute a receiver NOT in a position to receive a catchable forward pass"?
I am of course talking about blocks that occur in accordance to Rule 9-3-4-e, which actually leads me to interpret Rule 7-3-9-c as to ruling the receiver running the curl route as NOT "in a position to receive a catchable forward pass".
Defensive players may ward off or legally block an eligible pass receiver until that player occupies the same yard line as the defender or until the opponent could not possibly block him. Continuous contact is illegal (A.R. 9-3-5-I).