Potential Screen
 

V match (if it matters). Libero is LB. Just prior to the server contacting the ball, L would run near the end line directly in front of the server, from the server's left to the server's right.

This only happened in this rotation (not the similar rotation 3 rotations later when L is also LB).

Would you call the screening violation? Subtly try to tell L not to do it? Ignore it? Other?

First we need to make sure all the elements of screening exist. Does the server serve the ball directly over the L who is running past her? Is the serve low and fast? Are players on the receiving team having to adjust or move their positioning because their view is "screened" by the L running past the server? If all this is not occurring, then we don't have a screen. Next would be is the L in the correct position at the time of the server contacting the ball? If she is, then there is no illegal alignment issue. There is nothing in the rules that says players cannot move around. As long as they are not violating the rules in the rulebook, let it go.

Yes,the low and fast serve was directly over the L. The receiving team didn't adjust, but a couple of serves were aces (I recognize that's not the rule). L was in the right spot and remained in the right spot.

I did let it go -- but thanks for the info; it's helpful