Ten-point Must System
Nearly all professional boxing matches use a method of scoring called the ten-point must system. Using this system, matches are scored on a round-by-round basis in which the winner of a round receives ten points, and the loser of the round usually receives nine or fewer points.
This system is not generally understood by the general public for several reasons, but the primary reason being that the system is complicated and may change slightly depending on where the fight is being held. For example, in Great Britain there is a half-point system in use for some non-title bouts. Even inside the United States the system is not universal: Illinois uses a five-point system. However, most fights in most jurisdictions use the ten-point must system, which is described here.
In early bare-knuckle fighting days, there was no scoring system and fighters simply fought until one fighter could not continue. Each knockdown in the fight was considered a "round". As the sport matured and adopted the Marquess of Queensbury rules, referees, judges and standard rules were incorporated, including scoring for matches which were not finished (i.e., both fighters were still able to continue) after the alotted number of rounds.
These rules developed slowly over time to incorporate the idea that not all fights should continue to the point of annihilation of a participant. In the event of a decision, judges should follow a standard system to determine the winner without relying on their gut feelings.
The ten-point must system allows some scoring flexibility when a fighter totally dominates his opponent during a round, as opposed to winning a round by a small margin. The system also allows the referee to deduct points for rule infractions during the bout. Therefore under the ten-point must system it is possible for a fighter to win a greater number of rounds, but still lose the match due to having fewer points.
Rounds are scored by judging four areas of performance. Each area should theoretically count for 25% of the score for a given round. The areas are: clean punching, effective aggressiveness, ring generalship and defense. In practice, clean punching counts for more than the other three since in boxing, the clean punch is the only weapon against an opponent. The other three criteria are used when necessary to score a close round.
Effective aggressiveness means being aggressive toward your opponent while landing clean punches. If you move toward your opponent but can't land clean shots, you don't have effective aggressiveness.
Ring generalship is a measure of who is controlling the ring. For example, you will often hear boxing announcers talk about how a boxer is "cutting off the ring" and keeping the opponent contained, often cornering the opponent.
Defense is exactly as it sounds -- when a fighter is able to defend against punches from the opponent. Generally this means ducking, blocking, or backing up. Defense is generally considered the least important of the four scoring criteria.
For each round, judges determine the score using the ten-point must system. This means that (usually) the winner of the round gets ten points, and the loser gets nine points. There are exceptions to this rule. For example, when a fighter is knocked down, that fighter loses a point. So if the fighter that was knocked down loses the round the score would be 10 to 8 for that round. If the fighter that was knocked down wins the round (which is rare) the score would be 9 to 9. If a fighter is knocked down twice, the score would normally be 10 to 7 for the round. If three knockdowns occur you should have a 10 to 6 round, etc. Also, it is possible for a judge to score a round as a tie, which is exceedingly rare. In this case the score for the round would be 10-10.
If each fighter scores a knockdown, the knockdowns effectively cancel each other out and the score returns to 10 points for the winner and 9 points for the loser of the round.
It is the referee's job to determine whether a knockdown occured. Sometimes what looks like a knockdown will be ruled by the referee to be a slip, or vice-versa. In this case the judge should always reflect the referee's ruling in the scorecard.
If the winner of a round wins by a very large margin, the judges may deduct another point from the loser of the round. This is to award the fighter who completely dominates a round in all four scoring areas. So if a fighter wins a round by completely dominating the opponent, the score could be 10 to 8. Judges are not required to deduct an extra point from the loser in this rare (and subjective) situation.
Penalty points are only determined by the referee of the bout. In the event of a foul, it is the referee's job to determine the number of points to deduct from a fighter's score for that round and to notify the judges to make the deduction.
In the event that each fighter has penalty points deducted during a single round, the penalty points cancel each other out. If fighter A has 2 penalty points while fighter B has 1 penalty point, the judges would simply deduct 1 point from fighter A since the first penalty points from each fighter are canceled out.
Penalty points are always deducted from the final score for a round. If a fighter scores 2 knockdowns in a round and wins that round, the score would be 10-7. If that fighter incurred 1 penalty point in that round, the score would be 9-7.
Determining the Winner
Normally, scorecards are collected by the referee at the end of each round, and judges are not allowed to change their score after it is turned in. In a close fight, a judge may not even know who is winning at any given time. At the end of the fight, the fighter with the most points on each scorecard wins.
In most professional bouts, there are three judges. In the event that the judges scorecards show different results, you have what is called a "split decision" or "majority decision". In this case the winner is the one shown on the majority of the cards. If 2 of the 3 judges score the bout a draw, the bout is called a "majority draw".
Kaczmarek, Tom, "You be the Boxing Judge", Dorrance Publishing Co., Inc. (Pittsburgh, PA, 1996)
Lederman, Harold, "Harold Lederman on Scoring", hbo.com, 2000, http://www.hbo.com/boxing/cmp/scoring.shtml