Goal-line technology in the Premier League: how the system works

Goal-line technology in the Premier League is the Hawk-Eye camera system that tells the referee whether the whole of the ball crossed the line. It has been in use since the 2013/14 season, when the league became the first major domestic competition to adopt it. Seven cameras trained on each goal track the ball, and when it fully crosses the line an encrypted signal reaches the referee's watch within a second; the system answers only the goal-or-no-goal question, leaving everything else about a goal to the video assistant referee.

How the system works

Hawk-Eye works by triangulation. There are seven cameras at each end of the stadium focused on the goals, most commonly mounted on the roof, and the software processes their images to find the ball and identify areas that are not the ball. Because the cameras track it from different angles, they can tell when the whole of it crosses the goal line between the goalposts and under the crossbar. That moment triggers a signal, within a second, to a watch Hawk-Eye developed exclusively with Adeunis. The referee gets a vibration and an optical signal, and the transmission is encrypted and unaffected by interference.

The speed is the point. IFAB, the body that writes the Laws of the Game, requires goal-line technology to detect the ball automatically and send its signal within one second, and its testing criteria originally demanded the message in less than 0.5 seconds. FIFA's quality programme adds four requirements: the system must address only whether a goal was scored, it must be accurate, it must confirm immediately within one second, and it must communicate solely to the match officials. Broadcasters get the replay within 10 seconds, thanks to a dedicated high-speed camera that can strip the players out of the image, so the definitive angle reaches TV before the restart.

Accuracy is where the system earns its keep. Hawk-Eye betters FIFA's margin-of-error requirement of +/-3cm, and IFAB's earlier stipulation asked for accuracy within 5mm. The seven cameras can locate the ball even when only a small percentage of it is visible, which is why a goalmouth scramble rarely stops a correct call.

Why the Premier League adopted it in 2013/14

Goal-line technology exists because of a goal that was never given. Frank Lampard's disallowed "ghost goal" for England against Germany at the 2010 World Cup, when the ball clearly bounced over the line only for play to continue, pushed the lawmakers into action. FIFA president Sepp Blatter said that incident played a decisive role in the decision to allow technology.

The Premier League had been working with Hawk-Eye since 2006, when IFAB gave permission to test the system in a non-competitive environment. An initial camera-based system was trialled at Fulham's Craven Cottage during the 2006/07 season, with tests moving to Reading's Hogwood Park training ground in 2007. IFAB voted unanimously in July 2012 to amend the Laws of the Game to permit, but not require, goal-line technology. On 11 April 2013 the 20 Premier League chairmen voted to adopt it from the 2013/14 season, and the FA installed a system at Wembley in time for that August's Community Shield.

The first Premier League goal awarded by the technology came on 18 January 2014, when Edin Dzeko's goal for Manchester City against Cardiff City was confirmed over the line. It also happened to be City's 100th goal of the season.

How goal-line technology interacts with VAR

The two systems divide the labour cleanly. Goal-line technology settles one question: did the whole ball cross the line? VAR reviews four match-changing decisions, including goal/no goal, and checks the phase around a goal for offside, fouls in the buildup and handball, as our guide to VAR sets out. When the watch buzzes, the goal stands on the line question and the rest of the phase still gets checked. When it stays silent, there is usually nothing to debate.

Usually is doing work there, because the system has failed once in Premier League history. In June 2020, in the first match after lockdown, Aston Villa's Orjan Nyland carried the ball over his own line after fumbling a free kick against Sheffield United. Referee Michael Oliver received no alert, no goal was given, and the game finished 0-0. Hawk-Eye said in a statement that seven cameras in the stands around the goal area were unable to identify the ball at that moment because of significant occlusion: Nyland, a Villa defender and the goalpost obscured its position over the line from the cameras. The company said that level of occlusion had never been seen in over 9,000 matches. PGMOL, which runs the match officials, said that under IFAB protocol VAR is able to check goal situations, but because the on-field officials received no signal, the VAR chose not to intervene.

That case exposes the one design weakness worth arguing about: a protocol that trusted a silent watch over a visible replay. It is also the strongest argument for keeping the two systems separate. GLT is the fastest and least intrusive technology in the game. No stoppage, no monitor visit, no delay to added time; a decision that once triggered a goalmouth scramble now triggers nothing at all, which is exactly how a goal-line call should feel.

Common confusions

The biggest one: goal-line technology is not VAR. It does not judge offside, handball or fouls, and it does not review anything. It is a single-purpose sensor, nothing more.

The whole ball must cross the line. Football only counts a goal when the entire ball is over the line, and the system signals only that event, between the posts and under the bar.

It is not everywhere. The Laws permit goal-line technology but require its use to be stipulated in competition rules, which is why it is in place only where a competition chooses to adopt it. In the Premier League, every ground has it.

It does not slow the game. The signal arrives within a second, before most fans have finished appealing for the goal, which is why every goal that crosses the line in the live match centre is confirmed before play restarts and why goal-line technology is the least controversial addition to modern football.

FAQ

Has goal-line technology ever failed in the Premier League? Once. Aston Villa against Sheffield United in June 2020, when all seven cameras were blocked and no goal was signalled despite the ball crossing the line. Hawk-Eye said it was the first failure in over 9,000 matches.

Does goal-line technology replace VAR? No. GLT judges only whether the whole ball crossed the line. VAR reviews the rest of the goal phase, including offside, fouls in the buildup and handball.

How accurate is goal-line technology? Hawk-Eye betters FIFA's margin-of-error requirement of +/-3cm, and IFAB's original testing criteria demanded accuracy within 5mm with the signal delivered in less than 0.5 seconds.

When was goal-line technology introduced in the Premier League? From the start of the 2013/14 season. The 20 clubs voted for it on 11 April 2013, after the 2010 World Cup ghost goal had forced the debate.

Key takeaways

• Premier League goal-line technology is Hawk-Eye: seven cameras per goal, an encrypted signal to the referee's watch within a second, in place since 2013/14.
• It answers one question only, whether the whole ball crossed the line, and it betters FIFA's +/-3cm margin-of-error requirement.
• IFAB approved goal-line technology in July 2012, and the first Premier League goal awarded by it was Edin Dzeko's for Manchester City in January 2014.
• VAR handles everything else about a goal; in the system's one Premier League failure, Aston Villa against Sheffield United in 2020, VAR did not override the missing signal.
• The 2010 World Cup ghost goal that denied Frank Lampard is the reason the technology exists at all.