Basketball arbitrators, also known as referees or REFS, are responsible for ensuring that the rules of the game are followed and that the players are playing fairly. They are responsible for making calls on the court, such as fouls, violations, and out-of-bounds plays. They also have the authority to issue technical fouls and eject players from the game. REFS must be knowledgeable about the rules of the game and must be able to make quick decisions in order to keep the game running smoothly.