Video assistant referee

The video assistant referee (VAR) is a football assistant referee who reviews decisions made by the head referee with the use of video footage and a headset for communication. In 2018 VARs were written into the Laws of the Game by the International Football Association Board (IFAB) following trials in a number of major competitions.

Procedure
There are 4 types of calls that can be reviewed.
 * Goals and whether there was a violation during the buildup
 * Penalty decisions
 * Red card decisions (second yellow cards are not reviewable)
 * Mistaken identity in awarding a red or yellow card

The standard for overturning the referee's original decision is that there has been a "clear error", sometimes expanded to "clear and obvious error".

The process begins with the video assistant referee(s) and the assistant video assistant referee (AVAR) reviewing the play in question on a bank of monitors in the video operation room (VOR) with the assistance of the replay operator (RO). This can be triggered by the referee requesting the review or by the VAR conducting a "check" to see if he or she should recommend a review to the referee. If the VAR finds nothing during the check, then communication with the referee is unnecessary, which is called a "silent check". If the VAR believes there has been a potential clear error, he or she will contact the referee with that judgment. The referee can then either (a) change the call on the advice of the VAR or (b) conduct an on-field review (OFR) by going to a designated spot on the sideline, called the referee review area (RRA), to review the video with the help of the review assistant (RA) or (c) decide that he/she is confident in the original call and not conduct an OFR. The referee is allowed to stop play to reverse a call or conduct an OFR, but is not supposed to do so when either team is engaged in good attacking possibility.

The official signal for a video review is the referee making the outline of a rectangle with his index fingers (indicating a video screen). This precedes both any OFR as well as any change in the original call. Players who demand a video review by making the rectangle motion are to be cautioned with a yellow card. Players who enter the area where the referee conducts an OFR are also to be cautioned with a yellow card, and team officials who do so are to be dismissed.

There are guidelines the referee and the VAR should follow in conducting a video review. For example, slow motion should only be used for "point of contact" offences, such as physical offences and handballs. Regular speed should be used to determine the intensity of an offence and whether a handball was deliberate. Reviews for goals, penalty kick decisions, and red cards for denial of an obvious goal scoring opportunity cover the period back to the beginning of the "attacking possession phase" (APP), when the attacking team first gained possession of the ball or restarted play. Other reviews only cover the incident itself.

The VAR will be a current or former referee.

History
The International Football Association Board (IFAB), the body that determines the Laws of the Game, approved the use of video referees in trials during its 2016 Annual General Meeting.

A live trial of the VAR system began in August 2016 with a United Soccer League match between two Major League Soccer reserve sides. Match referee Ismail Elfath reviewed two fouls during the match and, after consultation with video assistant referee Allen Chapman, decided to issue a red card and a yellow card in the respective incidents. Video reviews were introduced the following month during an international friendly between France and Italy. A "pitchside monitor" was introduced at the 2016 FIFA Club World Cup, allowing referees to review footage from the field. The A-League in Australia became the first to use a VAR system in a professional league game on 7 April 2017, when Melbourne City played Adelaide United. The game was completed without the VAR being called upon. The first intervention by a VAR in a professional league game was seen on 8 April when Wellington Phoenix hosted Sydney FC. The VAR identified an illegal handball in the penalty area and awarded Sydney FC a penalty. The game finished in a 1–1 draw.

Major League Soccer in the United States introduced VARs in competitive matches during its 2017 season after the 2017 MLS All-Star Game on 2 August 2017. Its first official use came during a match between the Philadelphia Union and FC Dallas, invalidating a goal from the latter over contact made between a Dallas player and Philadelphia's goalkeeper. VAR was used at the 2017 FIFA Confederations Cup in June, where it was praised but its usefulness was questioned after a referee decision in the final match. The system was introduced to most top-tier European leagues at the beginning of the 2017–18 season, with the exception of England's Premier League. The system was also used at the 2017 FIFA U-20 World Cup in October.

On 8 January 2018, VAR was trialled for the first time in England in the 2017–18 FA Cup game between Brighton & Hove Albion and Crystal Palace., and the following day it was trialled for the first time in France in the Côte d'Azur derby game in the French League Cup — it was said to have worked well.

Italy opened the world's first VAR training centre in Coverciano in January 2018.

On 3 March 2018, the IFAB wrote the VARs into the Laws of the Game on a permanent basis. Their use remains optional for competitions, and the English Premier League and the UEFA Champions League are not expected to implement VAR for their 2018–19 seasons. FIFA officially approved the use of VAR for the 2018 FIFA World Cup during the FIFA Council meeting on 16 March 2018 in Bogotá.

Assistant video assistant referee
The assistant video assistant referee (AVAR) is a current or former referee appointed to assist the VAR in the VOR. The responsibilities of the AVAR include watching the live action on the field while the VAR is undertaking a "check" or a "review", to keep notes of incidents, and to communicate the outcome of a review to broadcasters.

Criticism
During the 2016 FIFA Club World Cup Final in Japan, the first trial of the VAR in an international club competition, Real Madrid manager Zinedine Zidane called the system a source of confusion.

The use of video technology at the 2017 FIFA Confederations Cup was criticised after several contentious moments involving VAR at the tournament. It was accused of "creating as much confusion as clarity".

Controversy
In a Primeira Liga game between Boavista and Aves in February 2018, an Aves goal that many felt was offside was allowed, after it was discovered that a Boavista supporter's flag had been obscuring the VAR camera. With no VAR evidence available, the referee was required to let the goal stand.

In a Bundesliga match between Mainz and Freiburg in April 2018, players were instructed to return to the pitch, having left for half time, after VAR determined that a penalty was due.

In the 2018 A-League grand final between Newcastle Jets and Melbourne Victory, VAR failed to overturn a Melbourne Victory goal due to an offside. It was later revealed that the VAR software suffered a technical malfunction which prevented the assistant referee to view the replay. Melbourne went on to win the game 1-0.