I can't help but think... What if the cops had simply stayed away and let the party end? Booze runs out, music turns off and kids go home. Sorry I know this isn't PC and others will not agree. Sure there was underage drinking but I've yet to read of anything happening, aside from a large party, before the police showed up.
Being from Canada the legal drinking age is 19. I've never understood the age of 21 here in the US. I knew most people at school (high school) including the nerds, jocks, bad boys, potheads, honor students, etc. Between myself and 3-4 friends we hosted parties most weekends during the spring, summer and fall months which would have included typically anywhere from 100 to 350 people. A few grew to about 700. We'd invite our friends who'd invite a few of theirs and boom, instant party. Cerwin vega speakers on the roof powered by Realistic equipment from Radio Shack, small fireworks being fired off over head throughout the night, bonfires with 6' logs tossed on, a volley ball net strung up and depending on the yard swimming in the pools or lake. Anyone got out of line simply got asked to leave.. A few got tossed out with some persuasion but left with friends to calm them down.
Ok so yeah some underage drinking took place and some minor injuries happened but nothing big. It's part of growing up. Sure we did it more them most others but for the most part everyone had fun and no one really got hurt. Everyone pretty much looked after others.
That said.. My father always said I had good Common Sense and he never worried much when I was out or they were away (knowing full well a party was taking place).
I guess that's the biggest problem these days. Neither the kids or most adults these days have any Common Sense.