In ultimate, there is no concept of intentional vs. unintentional fouls: infractions are called by the players themselves and resolved in such a way as to minimize the impact of such calls on the outcome of the play (sometimes resulting in "do-overs" where the disc is returned to the last uncontested possession), rather than emphasizing penalties or "win-at-all-costs" behavior. If a player disagrees with a foul that was called on them, they can choose to "contest" the infraction. In many instances, a conversation ensues between both parties involved in the foul, and a verdict is determined as to whether the disc will be returned and a "do-over" will commence, or if the person guilty of the foul has no objections to the call. A common infraction, intentional or not, is a "pick" where the offense (or your own team member even) is somehow in the way of your pursuit of your "person" in person defense. This only applies when you are within 10 feet of your "person" and the game play is stopped so that the players involved go back to where the "pick" occurred. The integrity of ultimate depends on each player's responsibility to uphold the spirit of the game.