The rules seem to be very clear on the matter. Players are not allowed to penetrate under the net and interfere with the opponent’s play. The following sequence occurred at the most recent FIVB World Club Championships.
As you can see, upon video review the call was made that this was a fault. That is, the player did in fact interfere with the play of his opponent. Upon review after the match, the referee was deemed to have made the wrong call. The player did not interfere with his opponent’s play, because that opponent was not in the act of playing the ball. Indeed the relevant interpretation asserts that even contact with an opponent is not necessarily a fault, if the opponent was not in the act of playing the ball.
In volleyball, every player is playing at all time, even if they are not touching the ball. In the above action the player under the net interferes with the opponent not just once, but twice.
Firstly, as soon as his eyes are taken away from the relevant cues (as above, in order to see where the player is) the blocking player has been interfered with. He is not able to properly prepare to play the ball due to the actions of the player under the net.
Secondly, the blocker’s freedom of movement has been compromised. With an opponent under or close to his feet, he does not have free movement on his own side of the court. Indeed, if the blocker had not looked down, his movement to prepare to block a high ball would have been to shuffle to his left. If he had fallen over the player, it still would not have been a fault, according the interpretation.
In the photo above, you can clearly see the sweat trail that is left behind. In addition to interfering with play, he has created a dangerous situation that can lead to injury. If the blocker had slipped on this sweat and sprained his ankle, it would still not have been a fault, according the interpretation. Sweat from my own team through our own actions is a reasonable part of the game. Sweat from the opponent, on my own court, clearly interferes with play.
Sometimes the rules are wrong. Or they are interpreted in a such a way as to be inconsistent with the way the game is actually played.
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