The game is intense. The game is fierce. The game has no refs.
Ultimate frisbee is one of the few competitive team sports that
does not have an umpire, a referee, or an official. That's because frisbee doesn't need 'em.
Frisbee is a gentleman's sport. It was built on the idea that teams can play competitively and with intensity, but still be civil without mommy, daddy, or the guy who looks like a zebra to separate them when things get heated. As much as you want to win, you must respect your opponents as people.
There are plenty of fouls that can be called, but they are called by the players. Usually the person most involved with the play in question calls the shots. This can be tricky on skin-of-your teeth plays where no one is going to see the instant replay cameras, but more often than not honesty wins out. Other player on the field or on the sidelines with a good view are often expected to share their best, most honest ruling.
Part of being a good player is knowing not only when to call a foul, but when to keep your cool. Using discretion in the midst of a heated battle can be difficult, but it must be learned. Yes, games can get out of hand. But the best solution is let your game do the talking. Talking or playing dirty is never a desirable solution. You and your team must keep each other in check should someone start getting his or her panties wadded.
Frisbee is a gentleman's game, and purists and disc heads and new players all agree that is is the only way it should be.
Long live sportsmanship. Long live frisbee.