Try prevented

After Kurtley Beale was penalised the Waratahs are again penalised. This produces a five-metre line-out for the Sharks. Their intentions are obvious - a maul for a try to win the match.

Bismarck du Plessis throws in and near the front, Wilhelm Steenkamp rises high and catches the ball. The referee penalises the Sharks for obstruction.

When Steenkamp was up in the air, Jannie du Plessis moved behind him and came between him and the Waratahs.  Du Plessis was a lifter in the line-out and stayed in contact with Steenkamp as he moved towards the Waratahs, blocking them from getting to Steenkamp to sack him. There was no maul when Du Plessis moved into his blocking position. It became a maul when Waratah players made contact with the Sharks, but by that time Jannie du Plessis was between them and Steenkamp, blocking their access to him and preventing them from sacking him, which would have been a legitimate way to prevent the maul.

The referee was perfectly correct. In fact it is one of the Big Four that referees have been told to apply.

10.1 OBSTRUCTION
(c) Blocking the tackler. A player must not intentionally move or stand in a position that prevents an opponent from tackling a ball carrier.
Sanction: Penalty kick

What was not right was the place where the referee gave the mark, the place for the penalty. He gave it where the obstruction occurred but it was still a line-out and the pennalty should have been 15 metres in from touch.

There is, naturally, the goose-and-gander principle. What is good for the goose is also good for the gander. In the line-out following this one, Ben Mowen goes high to catch the ball and Will Caldwell goes in behind him before a maul if formed. To be fair it is not as clear and obvious as was the Du Plessis case.