Competition Area and Costume
Judo is a form of combat involving various types of holds, throws, and falls. Through most of the action, both competitors are on their feet.
The contest area is a square ranging from 27 to 30 feet on a side; it is usually bordered by Oriental mats called tatami. In minor tournaments, 24-by-24 contest areas are employed; for junior competition the measurements are 20 by 20.
The white, loose-fitting costume is called a judogi. The uwagi (jacket) is long enough to cover the buttocks and is tied at the waist with a judo belt (obi); the sleeves must extend at least halfway down the forearm. The trousers must reach at least halfway down the calves of the legs. For identification, one contestant wears a red sash, the other a white sash.
Progress of Competition
A referee and two judges officiate in an important match. The referee has overall responsibility for the conduct of a match. If a judge disagrees with a referee's judgment call, the judge may stand up to get the referee's attention. After discussion the referee may adopt the judge's decision or reject it. The referee's judgment is final. However, if both judges agree on the point at issue, in opposition to the referee, the referee must defer to them.
A contest lasts a predetermined time, from 3 to 20 minutes. If there is no clear winner, there may be an overtime period. Overtime ranges from 2 minutes for a 3-minute match to 7 minutes for a 20-minute match.
The match begins with opponents about 12 feet apart, the referee between them. After bowing to one another, each takes a step forward and waits for the referee's command to begin: "Hajime."
The winner is the first contestant to score an ippon (full point). There are many ways of doing this, including the combination of two waza-ari. A waza-ari, generally called a half-point, is actually somewhat closer to being a full point.
An ippon is scored when a contestant throws the opponent so that the latter lands with appreciable force on the back or side. Landing on the stomach or on the hands and knees may be ruled a waza-ari.
An ippon is also scored when a contestant gives up; either contestant can surrender by saying "maitta" or by tapping the body, the opponent's body, or the mat twice with hand or foot. This generally happens because a contestant is being choked or is unable to escape from a hold (usually an elbow hold) that could break a joint. An ippon is also scored when a contestant, using skill and approved techniques, lifts the opponent, face up, to shoulder height.
Victory also results when a contestant keeps the opponent with back to the mat and under control for 30 seconds, or when a joint-endangering hold is maintained for the same period. In either case, the aggressor is given a waza-ari after 20 seconds of such action. A waza-ari may also be awarded for various rules violations by an opponent. Any two wazaari make an ippon.
All of the action is supposed to take place within the combat area. However, if a contestant makes a proper throw and the opponent lands outside the combat area, an ippon can be scored, provided the thrower remains within the combat area. If one contestant has a hold on the other, and they go out of the area, or are about to go out, the referee orders them to stay as they are, has the clock stopped, moves them into the center of the area, and then starts the match and the clock again. Thus, a contestant cannot break a hold by forcing the action outside the prescribed area.
If a hold or a pin has begun when time runs out, the contest continues until the hold is broken, or until the prescribed time for an ippon has elapsed, in which case the ippon is scored. If a throw has begun before time runs out, it counts as a wazaari or ippon even if time elapses before the thrown contestant lands.
Violations
Certain types of techniques are forbidden. Joint-endangering holds may be used only if a match involves two contestants of black-belt rank. Striking an opponent with hand or fist is not permitted. Some basic wrestling techniques are forbidden. A judo competitor cannot, for example, force an opponent to the mat in an attempt to pin the opponent; such an attempt must involve an approved judo drag-down or throw.
A contestant may not avoid contact deliberately, or adopt purely defensive techniques, such as holding an opponent at arm's length or deliberately stepping out of the contest area. It is also illegal to trip or tackle; to use a foot, hand, or forearm on an opponent's face; to use a legscissors hold; to use any hold that might injure the neck or vertebrae; or to use the open fingers in choking.
If a contestant is about to commit a violation, the referee can give the transgressor a warning, called a shido. For minor violations, the first penalty is called chui; the second, called keikoku, is the equivalent of a waza-ari. A major violation calls for a keikoku as the first penalty and hansoku-make, or disqualification, on the second.
Flagrant violations, unsporting conduct, and similar offenses result in immediate hansoku-make.
Since a waza-ari and a keikoku are approximately equivalent, one of each adds up to an ippon. A chui and a keikoku add up to disqualification.
Decisions
If neither combatant can score an ippon before the time has elapsed, a decision is necessary. Both judges and the referee take part, as in boxing. In the event of a tie, the referee's decision holds. (A tie, of course, can come about only if at least one judge votes for a draw.) If just one of the contestants has a waza-ari, that contestant is normally the winner. But there are other minor points that can enter into a decision.
Tournaments
A tournament may be conducted as a straight elimination, with the winner of a contest moving on to the next round and the loser dropping out. Major tournaments, however, including the Olympic tournaments, are conducted under a "bad point" system.
Under that system, a contestant who wins a match with an ippon or two waza-ari is given no penalty points; the opponent is given 3 penalty points. A winner by decision gets 1 penalty point, the loser 2 penalty points. A contestant is eliminated from such a tournament upon accumulating 5 penalty points.