Passouts-NSW, Australia

I was wondering what the legal staus is on passouts at parties is in NSW?
Been to a few all ages parties where once you leave the party you are not allowed back in (unless you pay again).
Are organisers permitted to keep you in their party all night without passouts?
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'Life can only be understood backwards but it must be lived forward'

it has to do with the liquor liscencing laws in your state.. here in perth a lot of events have passouts after xx:xx time or not at all (ie. delirious)
also a no pass out policy could easily be put in as a condition of entry (ie. condition of the contract), and as long as punters are notified that there are no passouts, then they have the right to charge you entry again.

Just a few thoughts...
I'm not sure of the situation in Sydney and Perth but Crasher Summer Sound System for us has no passouts whatsoever. I doubt it has anything to do with liquor licensing because ours is during the day but may have something to do with the City of Melbourne wishing to keep the party contained. What council wants however many offguts ravers running around the cbd in sight of the general population? I believe Utopia also had no passouts at any stage of the night(a friend of mine wasn't allowed back in after she left for a short time. It's ok she got back in though ) and that too was a massive.
There may be issues with liability for safety and matters of duty arising out of having such a large number of people with passouts. Should one of those attending leave and medical complications arise and it is later found out that he/she had been attending GatecrasherSSS, for example, this could result in a tremendous amount of negative publicity and consequent damage claims. On the other hand if a problem should arise and medical attention can be gotten to that person quickly, because there are no passouts and he/she is inside, then the potential for harm is reduced.