There are no referees, so who makes the calls and settles disagreements?

Ultimate is self-officiated under Spirit of the Game: players are responsible for knowing and applying the rules, with mutual respect, adherence to the rules and the joy of play as core tenets. Intentionally breaking a rule, or calling one that didn't happen, is cheating.

Making a call:

• Only the player on the infracted team who saw it with certainty calls it, loudly and immediately ("foul", "pick", "travel", "violation" and so on).
• Make calls only when the infraction matters to the outcome of the play or someone's safety is at risk.
• The player called can contest if they believe it didn't happen.

Resolving it:

• Both players explain briefly and listen. Most discussions should take no more than about 30 seconds.
• If you can't agree, accept that the call is contested: generally the disc goes back to the thrower and the stall resumes at the count reached plus one, or 6 if over 5.
• You may ask sideline players for perspective, and coaches only to clarify a rule, not to make the call.
• If no one had a good view of a line or up/down call, the disc goes back to the thrower.
• If you realize your call was wrong, say "retracted".

Observers: where an event uses them, a player involved in a dispute can ask the observer to rule, and that ruling stands.

Each team's spirit captain (the captains, if no one else is designated) raises and resolves Spirit issues with the other team.