Police withdrew rioting charges against 16 men, arrested after the Undie 500 tour mayhem in Dunedin, when they appeared today in Dunedin District Court.
Instead the 16 will face lesser charges, including disorderly behaviour likely to cause violence, obstructing police and resisting arrest.
Police were pelted with bottles and cars and mattresses were set alight in a night of disorder after 150 decorated cars and 1200 students from Canterbury University drove down to Dunedin on August 25.
Inspector Alastair Dickie said 69 people were arrested after the Under 500 event, and most had been dealt with by the courts.
"These (16) were the main focus. The others were peripheral offences," he told NZPA.
He said police decided to drop the rioting charge after consulting the Crown Solicitor. The charge was "very difficult to prove".
"We also explored an unlawful assembly charge but that is even harder to prove," Mr Dickie said.
Of the 16 who had been charged with rioting, 10 had pleaded guilty to the various lesser offences and six pleaded not guilty.