Sales will be banned tonight from 8.15pm - halftime in the Highlanders v Cheetahs game - until 10pm, a decision which ORFU general manager Richard Reid estimated yesterday would cost the union between $5000 and $6000 in profits.
The ban covers five liquor booths around the ground. Sales at the supporters' club and corporate areas are not affected because their liquor licences are held by separate licenceholders.
Dunedin City Council liquor licensing inspector Tony Mole said yesterday the boy was sold the beer at 4.52pm on March 19, the day of the game between the Highlanders and Crusaders.
The ORFU did not dispute the facts and the suspension was authorised by the District Licensing Authority on Monday.
Mr Reid said while he understood and respected the police decision to impose the penalty, the ban was "a bit of a bugger".
The sale was "disappointing", given the ORFU took significant action to try to stop sales to people under 18, he said.
"We have security people on each bar and anyone who looks under 25 is asked for proof of identity. We're all over it like a rash, but unfortunately, one person got through."
He said he understood the boy was turned away at the other four bars.
The large number of people at the game that day - an estimated 20,000 - might have also been a factor, he said.
Dunedin police alcohol harm reduction officer Constable Neil Kettings, who supervised the sting, said controlled purchase operations had been carried out at Carisbrook before and the sale last month was the first time an underage purchase had resulted.