Glossary of Judo terminology
Referees / judges conduct Judo contests and render the win / lose decision. There is one referee and two assisting judges. Decisions by the judging staff are final and cannot be challenged.
The referee normally stands in the contest area and conducts the contest from beginning to end, rendering all Waza and win/lose decisions. The referee and judges all use prescribed gestures to express judgments and indicate "Shido" (Instruction / Light penalty), etc.
The representative gestures used by the referee consist of the "Ippon" gachi (Win by ippon) gesture where one arm is raised vertically above the head, the "Waza-ari" gesture where one arm is extended laterally (parallel to the floor) with palm facing downward, and the "Yuko" (Effective / Moderate advantage) gesture where the same laterally extended arm is slanted downward at a 45-degree angle.
The representative gestures used by the two judges consist of the "Inbounds" gesture (inside the contest area) in which one arm is extended (with the thumb of the hand facing upward) in the direction that the boundary line is running, with the arm then being raised vertically over the head, and then lowered again to shoulder height; the "Out-of-bounds" gesture (outside the contest area) in which one arm is extended at shoulder height (with the thumb of the hand facing upward) in the direction that the boundary line is running, and then being swung back and forth horizontally two or three times; the "winner by decision" judgment in which the judge indicates the winner by raising either the red or white flag (blue or white flag in international contests) to indicate the winner. With arms extended toward the front at a 45-degree angle, and with a red flag in one hand and white flag in the other hand, the judge raises the arm with the flag color corresponding to the winner abruptly upward to a vertical position above the head.
If the bout is judged a "draw", the judge raises both arms (with both flags) vertically above his head.