Police have asked schools to warn students and parents off boozy after-parties during the ball season.
Every school in the Auckland region has received a letter from police asking them to tell students and staff that events where tickets are sold and alcohol served to underage people are illegal.
"Problems lie almost exclusively with the pre and after school ball functions," the letter states.
The reminder comes after several years of trouble with after-balls, which are often held in locations not revealed until the night itself.
Secondary Principals' Association president Tom Parsons said ball season was a worrying time for principals and school communities.
"I'm yet to meet a principal who has a good night's sleep on the night of the ball. I'm yet to meet a board chair who has a good night's sleep the night of the ball.
"And, you know what, schools don't really need to have them - it's not part of their curriculum. And they are condemned if they do, and they are condemned if they don't."
Diocesan School has already held its ball. Principal Heather McRae did not respond to questions on how the night went, and other schools were not keen to talk about their events.
After their ball last year, St Kentigern College students were taken back by bus to the school carpark, where parents collected them. An assistant to head of college Stephen Cole said the school would not comment on arrangements this year.
Other schools have previously threatened to cancel balls if they hear about after-ball planning.
Rangitoto College in Mairangi Bay cancelled its 2010 ball because of an after-ball event in 2009. Parents who organised it had promised to cancel it when senior staff found out, but it still went ahead.
But principal David Hodge said there had not been problems since the Year 12 and Year 13 balls restarted, and he believed parents' attitudes had changed.
"The whole thing seems to have died down really, in the sense that I think the idea of binge drinking opportunities for teenagers seems to have almost run out of fashion.
"I think that King's College tragedy was probably the last straw."
King's College has not held a mid-year ball since the death of student David Gaynor after the 2011 function.
Headmaster Bradley Fenner said the focus was on its graduation ball at the end of the academic year, attended by students and parents.
• Any events for which tickets are sold are not private functions and therefore have to adhere to the provisions of the Sale of Liquor Act.
• It is illegal to supply anyone under the age of 18 years with alcohol - even with a signed permission slip from a parent - if the parent is not in attendance.
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