This is a commonly missed center line violation by the second referee, but not here. The blocker (on the white team) directly in front of the R2 steps across the center line as she is spinning to turn and push off away from the net in order to transition from defense (blocker) to offense (hitter). This commonly gets missed because after the block is over and the subsequent ball is dug, R2’s think their responsibility for watching the net and center line ends as well. High school rules state there are no exceptions or allowances for that rule even after the block is completed. As second referees, we need to make sure our eyes stay with the players at the net as long as there is potential for a violation and not with the ball.
Here’s another one, except by the attacker on her transition away from the net after attacking:
Here’s one that is completely unintentional, but needs to be called:
And, of course, here’s our GKCOA center line video created by Don Sleet: