The really hard one.

There are just over four minutes to play at the FNB Stadium with its 95 000 spectators. New Zealand are in the ascendancy and attack going right. The ball goes from Piri Weepu to Dan Carter who gives to Cory Jane. Jean de Villiers with backing from Pierre Spies has Jane covered but for some reason Bryan Habana comes in on Jane, leaving McCaw an overlap. The big, strong man makes for the corner as Habana chases and De Villiers and Spies cover across. De Villiers tackles McCaw as the All Black captain plunges for the line. McCaw grounds the ball in in-goal. His feet end in touch. The referee refers the incident to the TMO who is a South African. The referee asks: "Try, no try?"

It is clear from the start that it is a difficult decision, partly because of what the camera shows and does not show.

A referee has to work on what happened - not what did not happen - and this applies to the assistant referee and the TMO. Not to award the try, he needs to see one of two things - that McCaw's right foot was in touch before he grounded the ball or that he did not ground the ball properly.

The problem was when the TMO could see the grounding, he could not see where the boot was and when he could see the boot, he could not see the grounding. To make a decision that the foot was out it needed to be clear and obvious. It was not clear and obvious. That is why he could report what he did report: "There is no clear evidence that the player was in touch before he grounded the ball and so you may award the try."

There is no question of benefit of the doubt or unsure grounding. Benefit of the doubt does not exist in rugby and the grounding was clear and correct.

The commentator mentions something interesting. What would happen if foot was grounded in touch and the ball was ground in in-goal at the same time? It does not apply to this incident  as there was no evidence at all that that is what happened.

But what happens at simultaneous?

The nearest we have is a 2009 Law Clarification (Ruling) by the IRB after a request by the South African Rugby Union:

Scenario: A player carrying the ball attempts to score a try. In the process of grounding the ball in the in-goal according to the law, he simultaneously (at exactly the same time) touches the touch-in-goal line with an arm, leg or any part of his body.

The Ruling of the Designated Members of the Rugby Committee

The player has touched the touch-in-goal line in possession of the ball and therefore the Referee will award a 22 metre drop out to the defending team.

It would seem from that that in this case the try would not be given but a line-out to the defending team five metres from the goal-line. But perhaps greater clarity should still be sought.