In association football, goal-line technology (sometimes referred to as a Goal Decision System) is a method used to determine when the ball has completely crossed the goal line in between the goal-posts and underneath the crossbar with the assistance of electronic devices and at the same time assisting the referee in awarding a goal or not. The objective of goal-line technology (GLT) is not to replace the role of the officials, but rather to support them in their decision-making. The GLT must provide a clear indication as to whether the ball has fully crossed the line, and this information will serve to assist the referee in making his final decision.
Compared to similar technology in other sports, goal-line technology is a relatively recent addition to association football; its integration having been opposed by the sport's authorities. In July 2012, the International Football Association Board (IFAB) officially approved the use of goal line technology, amending the Laws of the Game to permit (but not require) its use. Due to its expense, goal-line technology is only used at the highest levels of the game. Goal-line technology is currently used in the top European domestic leagues, and at major international competitions such as the 2014 Men's and 2015 Women's FIFA World Cups.
In association football, a goal is considered to be scored if the whole of the ball crosses the goal line between the goalposts and under the crossbar. In most cases, this is relatively unambiguous (goal nets being a low-tech way of verifying that the ball passed the correct side of the goalposts). Occasionally however situations occur when it is difficult for referees and their assistants to tell if a goal has been scored before a rebound, save, or defender's clearance from the goal area.
Since 2012, goal-line technology has been permitted in matches. However, it is not required, and its expense and relative newness means that it is only used at the highest levels of the game.
Text relating to goal-line technology can now be found within four of the Laws of the Game:
The Laws themselves are not specific as to the nature of Goal Line technology systems, however other documentation from FIFA, which is cited by the Laws, goes into more detail. The FIFA Quality Programme for GLT Testing Manual precisely define the requirements of the systems. Four basic requirements of a system are stipulated:
Only systems which pass FIFA's testing programme are permitted to be used in the game, and an installation in a particular stadium must also pass tests (see below). Additionally, as mentioned above, match referees are required test the performance of GLT systems prior to the beginning of games.
A Goal Line Technology system once installed in a stadium must pass a "Final Installation Test (FIT)" before it can be used in a match situation. The FIT comprises similar tests to the second phase of testing that new systems must undertake but further attempts to account for the dynamic conditions that each particular geographical area, stadium design, humidity, lighting and many other factors will have on the system. Once a system has been tested and passed by an accredited Goal Line technology Laboratory and registered with FIFA it can then be used for all official matches. To date FIFA have accredited four institutes who can perform such tests.
Due to the expense of goal-line technology systems, the technology is only currently used at the very top levels of the game. In domestic competition, goal-line technology is only regularly used in a few major European leagues: Serie A,Ligue 1, the Bundesliga, and the Premier League.
Currently there are four licensed providers: ChyronHego, Fraunhofer IIs, GoalControl, and Hawk-Eye Innovations. ChyronHego and Fraunhofer IIs sell the GoalRef system which is licensed by FIFA but is not currently installed in any stadium.
Prior to 2012, competitions were unable to implement technology as provision was not made for it in the Laws. The Laws of association football are controlled by the International Football Association Board (IFAB), a body on which FIFA holds 50% of the voting power, sufficient to veto any changes to the laws.
Compared to other sports, association football was late to allow technology to assist with in-game decisions. The matter was a subject of debate within the game for over a decade with the game's lawmakers resisting calls for its implementation.
Throughout the 2000s various incidents incited discussion as to the potential for goal-line technology in the game. The lack of use of technology in association football was contrasted with other sports, which had incorporated video replays and other systems into their rules.
In response to this, FIFA decided to test a system by Adidas in which a football with an embedded microchip would send a signal to the referee if it crossed a sensor going through the goal. According to FIFA president Sepp Blatter, "We did different tests at the Under-17 World Cup in Peru but the evidence wasn't clear so we will carry out trials in junior competitions in 2007". However, those trials did not materialise and by 2008, Blatter had rejected the system outright, describing the technology as 'only 95% accurate'. FIFA and IFAB were resistant to introducing technology in the game, voting in March 2010 to permanently ditch the technology.
Following several refereeing errors at the 2010 FIFA World Cup - including the disallowed goal in Germany's 4-1 victory over England, when Frank Lampard hit a shot from outside of the penalty box that bounced off the crossbar and over the line; the ball came back out and the goal was disallowed because the assistant referee did not call for a goal - Blatter announced that FIFA would reopen the goal-line technology discussion.
Before Euro 2012, UEFA president Michel Platini dismissed the need for goal-line technology, instead arguing for placing additional assistant referees behind the goal. However, in a Group D match with Ukraine losing 1-0 to England, the on-field officials did not see Ukraine's Marko Devi?'s shot briefly cross the line before it was cleared by England's John Terry.
Heeding calls for the use of technology, in July 2011 FIFA began a process of sanctioned tests that eventually resulted in the approval of the systems used in the current game.
The first stage of testing considered multiple goal-line technology systems, with the requirement that the system notified the referee of the decision within one second of the incident happening. The message needed to be relayed via a visual signal and vibration. Tests were conducted by Empa between September and December 2011.
Produced by a German company Cairos Technologies AG, alongside Adidas, the GLT system used a magnetic field to track a ball with a sensor suspended inside. Thin cables with electric current running through them are buried in the penalty box and behind the goal line to make a grid. The sensor measures the magnetic grids and relays the data to a computer which determines if the ball has crossed the line or not. If the ball does cross the line, a radio signal is sent to the referee's watch within a second. Adidas designed a ball that could suspend a sensor and keep it safe and intact even when the ball is struck with great force. Cairos claims the process is practically instantaneous, addressing critics' concerns that the technology might slow down the game. An older system developed by Cairos was trialled at the 2005 FIFA U-17 World Championship, but was found not to be fast or accurate enough.
On 25 February 2013, FIFA granted a licence to Cairos Technologies AG, enabling them to provide goal-line technology for use in FIFA-sanctioned competitions.
The Goalminder system has two co-founders, Harry Barnes and Dave Parden, who first thought of the system after their favourite team, Bolton Wanderers, was relegated due to a wrongly disallowed goal. The technology was not picked up at the time, but after Frank Lampard's disallowed goal in the 2010 World Cup, interest in goal-line technology spiked causing FIFA to investigate the possibility of sanctioning goal-line technology. The technology uses high-speed cameras built into the goal posts and cross bar to record images at 2000 frames per second and deliver visual evidence to the referee, in less than five seconds, to settle goal-line controversy. With this technology there is no calibration: just visual evidence. The system is thought to be cheaper because less expensive cameras will be needed and the field will not have to be dug into.
GoalRef features a passive electronic circuit embedded in the ball and a low-frequency magnetic field around the goal. Any change in the field on or behind the goalline is detected by coils embedded in the goal frame, which determine the scoring of a goal. By producing low magnetic fields around the goals, GoalRef creates the radio equivalent of a light curtain. As soon as the ball has wholly crossed the goal line between the posts, a change in the magnetic field is detected. A goal alert is then instantaneously transmitted to the game officials using an encrypted radio signal, with a message displayed on their wristwatches.
The Hawk-Eye system was first developed in 1999. Hawk-Eye is an existing technology currently used in cricket, tennis, snooker and Gaelic games being played in Croke Park by the Gaelic Athletic Association. It is based on the principle of triangulation using the visual images and timing data provided by high-speed video cameras at different locations around the area of play. The system uses high frame rate cameras to triangulate and track the ball in flight. The software calculates the ball's location in each frame by identifying the pixels that correspond to the ball. The software can track the ball and predict the flight path, even if several cameras are being blocked. The system also records the ball's flight path and stores it in a database that is used to create a graphic image of the flight path, so the images can be shown to commentators, coaches and audiences. The data from the system can also be used to determine statistics for players and analyse trends. The proposal involves placing seven cameras for each goal mouth around the stadium. The system is near real-time and referees will be notified on their encrypted watch in less than one second from the ball crossing the line. Critics of the system claim the system will slow down the game and that the statistical margin of error is too large. Both Roger Federer and Rafael Nadal have criticised the accuracy of the system in tennis (though Roger Federer now supports the use of the system in football).
On 3 March 2012, IFAB announced that 2 of the 9 proposed systems had proceeded to the second stage of testing. These were Hawk-Eye and GoalRef. In the second phase of testing, the manufacturer of the technology chose a stadium to test its technology in a number of imagined scenarios. Testing was also conducted in professional training sessions and in laboratories to account for different climatic conditions and other magnetic field distortions. Tests on the watch to be worn by referees were also be undertaken. The systems also each underwent testing in some competitive matches.
The German-Danish GoalRef technology underwent match testing in some Danish Superliga matches in the first half of 2012. Following the second phase trials, on 5 July 2012 IFAB approved GoalRef in principle, making it available for use in professional matches under a set of revised Laws of the Game. Each installation however would also require licensing approval for use in the individual stadium, on a 12-month basis. The 2012 FIFA Club World Cup was the first tournament where GoalRef was used by a match referee. Goal Ref was used for the first time on 6 December 2012 in the first match of the 2012 FIFA Club World Cup.
The first match to use the Sony-owned Hawk-Eye goal-line technology was Eastleigh F.C. versus A.F.C. Totton in the Hampshire Senior Cup final at St Mary's Stadium, Southampton in England on 16 May 2012. Although it used Hawk-Eye, the system had no bearing on the referee's decisions and the system readings were only available to FIFA's independent testing agency. The system was also in place for the technology's second test on 2 June for England's friendly match against Belgium.
Following the success of the trials, in July 2012 IFAB voted unanimously to officially amend the Laws of the Game to permit (but not require) goal-line technology.
In December 2012, FIFA announced it would introduce goal-line technology at the 2012 FIFA Club World Cup in Japan.Hawk-Eye technology was employed at Toyota Stadium, while GoalRef was used at International Stadium Yokohama.
In April 2013, FIFA announced that GoalControl, a camera-based system, would be used at the 2013 Confederations Cup and, if successful, would be implemented at the 2014 FIFA World Cup (in October 2013, FIFA confirmed the use of GoalControl at the 2014 FIFA World Cup.) Its system, GoalControl-4D, uses 14 high-speed cameras located around the pitch and directed at both goals.  Later in April the Football Association announced that Hawk-Eye would be used in the 2013-14 Premier League season. On 16 December 2013, it was announced that Hawk-Eye would be used in three of the four quarter-finals and any subsequent matches in the League Cup. The system was used when, on the very next day, the Sunderland - Chelsea quarter-final goal from Frank Lampard was allowed. The first goal to be decisively awarded using goal-line technology in the English Premier League was Edin D?eko's goal for Manchester City against Cardiff City on 18 January 2014.
The first World Cup tournament to use goal-line technology was the 2014 FIFA World Cup. In a 15 June 2014 group stage match between France and Honduras, the Honduran goalkeeper Noel Valladares dropped a shot from Karim Benzema into the goal for the first World Cup goal given by the technology.
In December 2014, the Bundesliga clubs approved goal-line technology that will be introduced at the start of the 2015-16 Bundesliga season. The league picked the cheaper Hawk-Eye system over two German technologies. The technology was also introduced for Ligue 1 for the start of the 2015-16 Ligue 1 season.
While advocates for goal-line technology maintain that it would significantly reduce refereeing errors during play, there are also criticisms of the technology. Much of the criticism came from within FIFA itself including former FIFA president Sepp Blatter. Apart from the criticisms revolving around the technical aspects of the two proposed technologies, critics point out that such technology would impact on the human element of the game and remove the enjoyment of debating mistakes. Sepp Blatter has been quoted as saying "Other sports regularly change the laws of the game to react to the new technology. ... We don't do it and this makes the fascination and the popularity of football".
A study suggested that in the 2010-11 Premier League season "errors took place nearly 30% of the time that video replays could help prevent", but some people claim that instant replays would interrupt the flow of the game and take away possible plays.
Other critics believe it would be prohibitively expensive to implement the technology at all levels of the game and particularly for smaller/poorer football associations. FIFA officials have expressed a preference for 'better refereeing' as well as more match officials over implementing the technology. Advocates in turn cite the many examples of incorrect goal-line decisions deciding important games and point out that the technology has improved much since the initial trials carried out by FIFA. Advocates contend that any extra help for the referee should outweigh arguments that it would lead to non-uniform rules (since not all football associations would be able to implement it).
In April 2013, MLS commissioner Don Garber confirmed that MLS would not adopt goal-line technology for the 2014 season, citing cost as the overriding factor. GoalControl installation would cost about $260,000 per stadium, and a further $3,900 for each game.
In early 2014, the vast majority of teams in the two divisions of the German Bundesliga voted against introducing goal-line technology for financial reasons. The costs per club would have ranged from EUR250.000 for a chip inside the ball up to EUR500.000 for Hawk-Eye or GoalControl. The manager of 1. FC Köln, Jörg Schmadtke, summarized the vote with "The cost is so exorbitant, that using this (technology) is not acceptable". World governing body FIFA are set to make £300,000 from the Premier League's decision to install goal-line technology in all top-flight stadiums before the start of next season. Each of the 20 clubs will have to pay FIFA £15,000 to install, test and receive the 'FIFA quality seal' for Hawk-Eye's camera-based system, which is expected to cost around £250,000 per ground in total. FIFA will also make an extra £15,000 from Wembley Stadium, which will have the technology installed for use in events such as the FA Cup semi-finals and final.