Video technology trials - what we know
Q: So, video technology is being used in the Premier League?
A: Not quite. Professional Game Match Officials Ltd are conducting non-live trials in which they are practising what a video assistant referee (VAR) would do if they were actually able to intervene in live situations. It is similar to experiments conducted in Holland which have progressed to live trials. The Premier League could see it next season.
Q Where else have there been live tests?
A: Italy's friendlies against France in September and Germany this week - which included a goal from Kevin Volland being ruled out for offside - were part of live experiments in which a VAR was in communication with the referee and could talk to him via a radio link.
Q: How exactly does it work?
A: VARs, who must be qualified referees, watch matches on screens at a remote location where they have access to multiple camera angles and instant replays of incidents. If a trial is live, the referee can consult a VAR for advice about an incident or the advice could be offered unsolicited. A time limit is normally placed on reviewing decisions and the referee has total freedom to ignore the VAR's advice.
Q: What decisions can be influenced or overturned?
A: Under protocols approved this year, decisions eligible for review are limited to incidents involving goals, penalties, red card offences and cases of mistaken identity. But if it works, there will be calls for it to be extended to rectify other obvious errors, while the prospect of teams being able to use challenges - like in cricket and tennis - has also been floated.
Q: Why can't the referee just look at the footage himself?
A: That is another option that has been discussed but it would be difficult to do that without stopping the match - and football's rule-makers' main priority with technology is minimising its impact on the flow of the game and avoiding the long pauses that occur when it is used in other sports. There is also a reluctance to allow controversial decisions to be shown on a stadium's big screen.
Q: What are the other pitfalls?
A: Football will have to get used to decisions being reversed and play being hauled back. The extreme case is that of a penalty appeal being refused and the opposition racing up the other end to score only for the referee to then award the penalty on advice from the VAR.
Q: When will a decision be made on a permanent rule change?
A: Provided the experiments are successful, it could be in place for the next World Cup, with live trials possible in the Premier League next season.