When Argentina played Australia, Sanchez tried a PK for goal, but the ball hit a post and rebounded into touch without another player touching it. Wayne Barnes awarded the lineout to Australia in line with Clarification 2 of 2006 which laconically says:
"If the penalty kick is for goal, then it is a lineout defending team to throw in.Law 21.4(d)."
It also adds "If the penalty kick is for touch, therefore no place kick, then it is a lineout attacking team to throw in."
21.4 (d) is now 21.4 (e). The kicker "must not place kick for touch" If he does so, the sanction is an opposition scrum at the mark for the penalty.
If a "place kick FOR touch" implies intention, then in this case it was obviously accidental, and a PK into touch leaves the throw with the kicking team.
If a "place kick FOR touch" includes accidents, then the outcome should be a scrum.
How did the Designated Members reach their conclusion?
Unfortunately I am not privy to the Designated Members decisions. I do not even know who the Designated Members are? So cannot help with how they came to this conclusion.
Like a policeman I do not write the laws, I just uphold them. In the example, which was a kick for goal, Wayne Barnes got the decision correct.
Ours not to reason why......
The Rugby Ref