In the 1800s and early parts of the 1900s, many countries (and some parts of the United States) officially banned boxing, and occasionally the police (usually when they felt their bribes were insufficient) would step in to stop the unlawful bouts (which, although unlawful, were still sanctioned by regional boxing commissions). Since boxing is now lawful almost everywhere in the world, the number of fights called no-contest has decreased dramatically since the beginnings of the 20th century. Referees were also known to stop bouts during this period, when they felt bouts were too slow due to lack of aggression from one or both boxers.
In the modern game, rules in the United States now dictate that any bout which ends prior to the completion of the 4th round, due to an accidental headbutt, is to be declared a no-contest. Prior to this, accidental headbutt stoppages, had been ruled a technical draw. Most other no-contests in boxing occur when unusual circumstances, which would include instances such as a bout being rained out, ring falling apart, or an unexpected injury caused by something outside of the boxer's control. One good example of an unusual circumstance occurred in 1983, on the undercard of the fight where Roberto Duran beat Davey Moore for the World Jr. Middleweight title at the Madison Square Garden, when Luis Resto and Billy Collins Jr. boxed ten rounds. Resto appeared to win the fight cleanly, and the scorers gave the match to Resto. But, it was later discovered that he had cheated by tampering with his gloves before the fight. The injuries Collins received affected his sight, and, upon finding out what Resto and his corner had done, the New York state athletic commission decided to change the result of the fight to a no-contest.
On January 20, 2007, Nikolai Valuev fought Jameel McCline in St. Jakob-Halle, Basel, Switzerland. Valuev won the match, and defended his title, when McCline suffered a dislocated knee in the third round when he tripped and fell. According to WBA rules, if there is no punch landed by the fallen boxer's opponent when he suffers an in-ring accident, the fight is declared null (a no contest), and in this case there was no visible punch landed by Valuev in the moment of McCline's accident. The WBA however, as of 28 January still has the fight result as a TKO victory for Valuev.
No Contest decisions in MMA are usually declared when an accidental illegal strike (the rules on which differ from each organization) causes the recipient of the blow to be unable to continue, that decision being made by the referee, doctor, the fighter or his corner. Each fighter receives a NC counted in their record and is scored as neither a win nor loss. Blows from intentional illegal strikes that force a fighter to be unable to continue are not declared a No Contest, but as a win and loss by disqualification for the appropriate fighters.
A recent and controversial no-contest decision in MMA occurred at the The Ultimate Fighter 5 season finale between Rob Emerson and Gray Maynard. Maynard knocked himself temporarily unconscious during a takedown of Emerson, who then submitted due to an aggravated injury of the ribs, both being unaware that the other fighter could not continue. While awaiting the official announcement many believed that Gray Maynard would be declared the winner, because Emerson tapped out and it appeared that Maynard was unharmed. The NC decision was made by the judges due to both fighters inability to continue. Footage from a different angle was then aired showing Maynard needing assistance from the referee to stand from the floor only to fall down again.