The outcome of tennis matches, especially at the very top level, can be decided by the smallest of margins. Matches can last for in excess of four hours and the player who wins the most points won't necessarily always win the match. A point here or there can be the difference between winning or losing a match and a few centimetres here or there can be the difference between winning or losing a vital point. This places a huge responsibility upon the chair umpire and his or her team of linesmen and women. The job of these officials is made particularly hard when you factor in the speed at which modern players hit the ball and the fact that some matches get played into the late hours of the evening when visibility is failing.
Given the difficulties that they face, it is actually very admirable that the officials get the vast majority of decisions right. However, it is inevitable that there are some times when they don't. Concentration levels waver, their view of the ball may be obstructed, and they may be faced with a very marginal decision on an Andy Roddick 140 mile an hour serve! The decisions made by the umpire and linesmen have always been controversial and many of us can remember the ranting raving of players, such as John McEnroe and Ilie Nastase, when decisions went against them. At times (such as when being called the pits!) they must have wondered if it was worth continuing in the game.
On the other side of the coin, it's also easy to sympathise with a player who has put their heart and soul into a five set match, only to see a cruel and clearly wrong decision end their hopes. Spectators, too, can feel cheated at seeing a match determined by a wrong call rather than a genuine moment of brilliance.
It was against this backdrop, therefore, that the tennis authorities started to review whether they could make use of modern technology to reduce controversy and improve the integrity of the sport. As far back as 1980, at the Wimbledon Championships, a system called Cyclops had been introduced to determine whether players' serves were in or out. It uses infra-red beams of light to determine whether the serve is in or out. Romanian maverick player, Ilie Nastase famously wasn't too sure about this new invention and got down on his hands and knees to inspect and talk to the Cyclops machine. These days, however, Cyclops is very much an accepted part of the tennis landscape. It was fairly logical, therefore, to look at whether modern technology could be extended to help with contentious decisions during rallies.
The technology that the tennis authorities chose to employ is called Hawk Eye and already had a good track record in other sports. For example, in test cricket matches the umpires are able to refer a decision to hawk eye to see whether the ball would have hit the stumps if a player hadn't blocked the ball with their pads. The International Tennis Federation (ITF) decided to trial the use of Hawk Eye in tennis in 2005 in New York. It was deemed a success and was sanctioned for use in major tennis tournaments.
One of the concerns over the use of instant replay technology in sport has been the potential for it to slow down play and interfere with the spontaneity and drama that is so essential to its appeal. For example, if players could query every line call, that could quickly become a bore and could also be used by unscrupulous players to gain a breather between points. Tennis resolved this fear in a very clever way, by stating that players would be restricted to a quota of appeals. When the Australian Open became the first Grand Slam event to employ Hawk Eye, in 2007, players were allowed two incorrect appeals per set and a further one if the set went to a tie-break. This meant that players had to think very carefully about the wisdom of appealing. Making an appeal when forty-love up on their serve might not be worth the risk but at 6-5 in the set and with a break point on their opponent's serve, then it might very well be!
The basic rules of tennis have not changed very much since the sport inception in the late Nineteenth century. However, tennis has shown a capacity to adopt the best that modern technology has to offer to enhance the product that it puts on display. The use of the Hawk Eye instant replay technology has been a huge success. In one fell swoop it has made the life of linesmen and women easier, has reduced the sense of injustice that players sometimes used to feel and has added excitement for spectators rather than diminished the viewing experience. At a time when some other sports, notably soccer, lag painfully behind, tennis has shown that it is a sport that is ready to embrace the times and make full use of the technologies that are available.
Sources:
http://en.wikipedia.org/wiki/Hawk_Eye#Tennis
http://en.wikipedia.org/wiki/Cyclops_(computer_syste m)