An Ashburton charity has canned two planned after-ball parties after police said it might be prosecuted.
The Ashburton Community Alcohol and Drug Service (ACADS) has run private parties for Ashburton College and Mt Hutt College students for the last 17 years.
But an out-of-control after-ball party in Napier has prompted Canterbury police to notify schools in the region they risk a fine if they charge for entry.
ACADS says as a charity it has to charge, and not running the events will mean a return to unsupervised private parties.
"We can't afford as an organisation to face prosecution and I can't ask my staff to do that either," ACADS general manager Chris Clark says.
"[We're] really disappointed. We felt we were looking after our young people and keeping them safe on this high-risk night."
Before the charity organised such after-parties, Ms Clark says they were held in the country and young people would walk home on dark country roads or attempt to drive.
The letter sent to secondary schools by police addressed parents and caregivers reads:
A decision from the courts only a few months ago now gives a much clearer indication as to what constitutes the offence of "Use of Unlicensed Premises as a Place of Resort for the Consumption of Alcohol".
The maximum fine is $20,000.
ACADS says at the organised parties students must have transport home or jump in the van provided. Around 30 parents help out on the night, with security on the gate. Food and 250 bottles of water are provided, and there's a six-drink maximum for each student.
Ms Clark says lots of kids don't drink if they have sport the next day.
Parents' permission is required and it's up to those with underage kids to decide how many drinks they were allowed.
"After-balls like ours probably don't happen in other areas, but it was specifically designed for our young people," she says.
Police say asking for a donation to cover food costs is also counted as an entry fee.
Mount Hutt student Emma Luscombe says students are "devastated". She is part of the school's welfare committee which helps organise the after-ball.
Emma says students feel they have nowhere to go after the ball to celebrate.
"In the long term it's not good because the after ball that we had is organised and it's safe and controlled," she says.
"Everyone's been pretty keen on trying to find another way around it but a lot of people are scared about the risks."
Mount Hutt College acting Principal Kristine Canham says the ball itself is not in jeopardy as it is a school event and the after-ball is not.