Police debrief following disorder after the arrival in Dunedin of an unofficial Undie 500 event last month has identified the emptying of a student bar as the main catalyst for events that followed.
Inspector Dave Campbell said the Castle St bar, the Gardens Tavern, did nothing wrong, but the link between the subsequent disorder and the release of hundreds of intoxicated people into the street at closing time was clear.
Police would consider what to do about the bar's closing time as part of planning for any future event, he said.
People danced in front of, jeered at and threw objects at police dressed in riot gear attempting to move groups off Castle St as a number of smaller parties on the street joined people leaving the Gardens Tavern about midnight on Saturday August 23.
The disorder was less intense than events after the 2007 Undie 500 event when about 60 people were charged after a night of fires, bottle-throwing and general disorder.
The official Undie 500 event was cancelled for 2008 and its future remains in question after this year's trouble.
Eight of the 30 people arrested on Castle St this year were later released without charge due to uncertainty over who had arrested them during the height of the disorder and on what basis, Insp Campbell said.
The other 22 are working their way through the court system.
Police have opposed diversion for only about 10 people, those arrested between 11.30pm and 1.30am - the time of the main disorder.
It is unclear how many of those 22 people are students.
No further arrests were made and police decided not to trawl through footage from the night's events because of the time and resources it would take, Insp Campbell said.
Asked why it seemed there was less public discussion of the disorder by the authorities this year, Insp Campbell said publicising the event had a negative effect.
"It's one of those things that's better to be played down, than played up."
University of Otago student services director David Richardson said the university had not decided what, if any, additional penalties it would hand down to Otago students convicted as a result of the disorder.
The university was confident it did everything it could to minimise the impact of the weekend.
"It was a disappointing outcome and I don't believe there is a quick-fix solution."
Mr Richardson was keen to discuss options for next year with all parties involved during a debrief with Dunedin mayor Peter Chin later this month.
