The introduction of advanced technologies like virtual assistant referees and goal line technology to professional football has so far been a great success, and an encouraging sign of things to come in the modern game.
Goal-line technology is a technical means of instantly determining whether the whole of the ball has crossed the goal line.The technology is being used at the World Cup for the first ever time, and has the potential to fundamentally change games. It could decide the future of the tournament, by reversing some of the most important refereeing decisions in the game.
Proponents claim that VAR will ensure that decisions are fair and that the best team wins. But even those supporters admit that the technology is still at a very early stage – with supporters and referees still apparently confused about how it should actually be used.
Despite that complexity, the technology is fundamentally incredibly simple: it is an extra referee who watches the game and advises officials on decisions. In practise, though, it might be very complicated indeed.
There are 13 officials who can be chosen as the video assistant referee. They will all sit in a special hub in Moscow – no matter where the game is happening – and they will do so wearing their full kit, as if they were ready to jump onto the pitch at any time.
Goal: The system can be used to check if a goal actually went in, in the obvious way. But it can also adjudicate on the lead-up to the goal, not just the ball passing into the net – if an infringement would have stopped the goal being rewarded, then VAR can stop it being awarded.
Penalties: This can go either way, being used to check whether a penalty should have been awarded and wasn't, but also reversing the decision if a foul is given in the penalty box.Red cards: If the referee has decided a foul has been committed, then VAR can be used to decide whether a red card should be awarded. This might be the most controversial thing that the video technology will be relied on for, for reasons we will get onto later.
Mistaken identity: Probably the most vague but also important parts of VAR's responsibility, this will allow the additional referees to spot if the wrong player has been disciplined. If they are, the referee will be corrected.
That should stop situations like the mix-up between Kieran Gibbs and Alex Oxlade-Chamberlain that saw the wrong player sent off during a match in 2014.
The systems were given the green light to be introduced into football late last year to give clear and quick decisions on goal line incidents and finally put an end to a controversy that has been part of the game for many years.
At present there are two manufacturers of the technology in use within the game, and the currently FIFA favoured GoalControl has been implemented at previous events such as the FIFA Club World Cup 2012 and the FIFA Confederations Cup 2013.
Success at these events has led to FIFA giving Goal Control permission to implement their systems at the forthcoming 2014 World Cup, to be held in Brazil next summer.
The Hawk-Eye system uses high frame rate cameras directed at each goal to detect where the ball is positioned relative to the goal line, and simply sends a signal to a watch worn by the match official to confirm whether the ball has crossed the line, with accuracy of millimeters.
This signal comes within a second of the incident occurring, ensuring minimal time is wasted and the match can continue. Definitive replays are also employed to prove the accuracy of the technology to the viewing audience.
Hawk-Eye has also signed an agreement with FIFA, which allows them to implement the system across the worldwide game. The system is now being trialled at the home of Dutch club FC Utrecht, with a view to expanding even further in the coming years.
Goal line technology is also of massive benefit to the referees and linesmen themselves, as the element of human decision in the most important part of the game has been overtaken by a system that will always work. Goal line technology gives a definitive answer to the situation and also makes the job of a referee significantly easier.
This information is transmitted within one second, which ensures an immediate response from the referee and that there are no stoppages or other forms of interference in the game. The match officials are the only ones to receive a signal. Unless the competition organiser decides to show a replay, this information is only available to the match officials.
Camera-based: Several approved systems work with cameras that detect the ball and use software to evaluate the footage from all the cameras. In this way, the system can determine whether the whole of the ball has crossed the goal line. Currently licensed systems work with seven cameras per goal installed as high up as possible within the stadium structure.
Magnetic fields: Several systems operate with magnetic fields. For these systems, cables are placed underground and around the goal, and the ball has elements of the technology inside. The interaction between the receptors in the ball and the magnetic fields created through the underground cables allow the software to calculate the exact position of the ball and determine when a goal has been scored.
Incidents: Two incidents involving England and Germany in 1966 and 2010 tend to dominate discussions and the perception of the typical goal-line incident. In recent years, there have been many more such situations. The following videos show a variety of goal-line incidents from the past couple of years.