Blocked Serve (NFHS)
 

I have always been under the impression that when any player blocks a served ball, an illegal block is called immediately. I just heard a very well-respected official say that a blocked serve is not considered illegal unless the ball goes back over the net off the block. Otherwise, it is simply considered a team's first hit. What say you?

9-6-5 Blocking a served ball is not permitted
9-5-1-c-2 Completed block- when the ball is touched by a blocker

It looks to me like the illegal block should be called immediately

I say your well-respected official is wrong. An illegal back row block is illegal when it's contacted, not when it goes back over. A block of serve is treated the exact same way.

Back when the rule was changed to not allow blocking the serve I do recall the interpretation being that the block was only illegal if the ball was blocked back to the serving team's side. I don't know if that interpretation was ever officially changed to consider the block illegal immediately on contact. It certainly may have, I just can't confirm that it did change.

I think that I would have a much easier time justifying the illegal block call on a serve that stayed on the blocker's side of the net than I would allowing the play to continue.

I think they are confusing an illegal block of serve and illegal attack of serve. An attack is not if it does not cross the net.
:D