Referee Craig Joubert did little to earn fans across the Tasman in the Super Rugby semifinal in Sydney, but in review it appears his calls were mostly right.

Saturday was a tough night for poor old Phil Kearns.

His beloved Waratahs were played off the park by the mighty Highlanders, and referee Craig Joubert, if Kearns is to be believed.

Last week we called out Justin Marshall for his commentary because of his lack of knowledge of the laws of the game. Other than a few laws that Marshall needs to brush up on, he is at least unbiased.

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Kearns on the other hand bleeds Waratahs blue, or at least green and gold, and he let it get the better of him in the commentary box on Saturday night.

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Taking off the green and gold goggles, how did Joubert really do refereeing the Super Rugby semifinal in Sydney?

Aaron Smith try - 18th minute

At first sighting, you have to wonder how Highlanders halfback Aaron Smith could have intercepted the pass from the back of the scrum by Wycliff Palu if he wasn't offside.

On closer inspection, you realise just how quick Smith is off the mark.

When the ball left the scrum, Smith is behind the ball and clearly onside. Even when the ball hit Palu's hands, Smith was still onside, standing behind Waratahs halfback Nick Phipps.

Having read the play so well, Smith sprinted into the path of Palu's pass and took the ball the other way for a try.

Smith was clearly onside, and Joubert was right to award a try.

Richard Buckman try - 32nd minute

When Buckman attacked the line he somehow squirmed his way through three defenders while falling to ground.

He then jumps up, steps another defender and sprints home for a try.

The question is, was Buckman ever tackled?

According to the World Rugby law book, "a tackle occurs when the ball carrier is held by one or more opponents and is brought to ground".

Further to that, "a ball carrier who is not held is not a tackled player and a tackle has not taken place".

Law 15.3 (a) states: "If the ball carrier has one knee or both knees on the ground, that player has been 'brought to ground'."

While Buckman was brought to the ground, when his knees come into contact with the turf the third tackler, Wycliff Palu, has just lost contact with Buckman - therefore Buckman was not held in the tackle.

Because he was not held when he went to ground, a tackle never took place and Buckman was free to jump to his feet and continue running.

Had Palu still been holding Buckman when his knee came to ground, Buckman would have had to release the ball before continuing towards the try line.

Again, Joubert made the right call when he said that Buckman was not held.

Patrick Osborne penalty try - 57th minute

This was the biggest call of the night with Joubert deciding to award the Highlanders a penalty try and yellow card Waratahs flanker Jacques Potgieter.

When Osborne gets within millimetres of the line, Potgieter swings his right forearm into Osborne's head during an attempted tackle.

To start, there is no doubting that Potgieter's tackle was a penalty.

He breaks two of the dangerous play and misconduct laws in the World Rugby law book.

Law 10.4 (e) Dangerous tackling states: "A player must not tackle (or try to tackle) an opponent above the line of the shoulders even if the tackle starts below the line of the shoulders. A tackle around the opponent's neck or head is dangerous play."

It also states: "A 'stiff-arm tackle' is dangerous play. A player makes a stiff-arm tackle when using a stiff-arm to strike an opponent."

Tick and tick.

To award a penalty try, Joubert had to decide if a try would have "probably" been scored but for the offending.

When Osborne takes the forearm to his head, his goal of stretching for the line goes out the window. There's nothing like a forearm to the head to change your train of thought.

Joubert decided that had Potgieter not intervened, Osborne probably would have forced the ball over the line, and it's hard to argue with that.

Foul play leading to a penalty try is an instant yellow card, meaning Joubert nailed the call.