Video Assistant Referee causes controversy every week in the Premier League, but how are decisions made, and are they correct?
After each weekend we take a look at the major incidents to examine and explain the process both in terms of VAR protocol and the Laws of the Game.
In this week's VAR Review: Why the penalty that earned Everton a point against Arsenal wasn't overturned, plus the early penalty claim for Fulham against top-of-the-table Liverpool. And was there an offside error on Wolverhampton Wanderers' winner at Ipswich Town?
Everton 1-1 Arsenal
Possible penalty overturn: Lewis-Skelly challenge on Harrison
What happened: Everton were awarded a penalty at the start of the second half when referee Darren England ruled that Myles Lewis-Skelly had bundled Jack Harrison to the ground. It was checked by the VAR, Stuart Attwell (watch here).
VAR decision: Penalty stands, scored by Iliman Ndiaye.
VAR review: If the Premier League doesn't want to see soft penalties, why didn't the VAR intervene to cancel a spot kick that most people would agree should never have been awarded?
As Lewis-Skelly and Harrison reached the edge of the box, the Arsenal player was leaning into Harrison. Lewis-Skelly ended up on the floor as the two players entered the penalty area, with Harrison going down too.
If the referee had given the penalty for holding by Lewis-Skelly, it could have been overturned as that potential offense took place outside the area. But the spot kick was awarded for Lewis-Skelly landing on the leg of Harrison and causing a foul, so that was the key aspect and the main focus of a VAR check.
Verdict: This is why supporters find it so hard to understand VAR. It's an incredibly soft penalty, and the Premier League's Key Match Incidents (KMI) Panel will vote that it shouldn't have been awarded. Yet the panel will also say it's not a "clear and obvious" error, so the VAR was correct not to intervene.
So we have a penalty that shouldn't have been awarded, but shouldn't be canceled because of the constraints of VAR protocol.
It's far more likely to happen the other way around, where the the KMI Panel believes the referee has missed a penalty but there's not enough in it for VAR. Of the 14 on-field errors that haven't reached the threshold this season, only one involved a penalty that was awarded -- to West Ham United against Aston Villa on the first weekend of the season. The KMI Panel hasn't logged even one missed intervention to overturn a spot kick.
Perhaps those stats show that penalties as soft as this one are pretty rare.
It's unlikely this would go to a VAR review in most leagues either, but certainly not in the Premier League, with the higher threshold for intervention.
Mikel Arteta says he's watched the decision to award Everton a penalty 15 times and still disagrees with the call.
Possible red card: O'Brien challenge on White
What happened: Everton had a free kick in the 15th minute. It was delivered into the area by Harrison, and Arsenal initially cleared their lines. As the ball was going out for a throw, Ben White went to ground in a tussle with Jake O'Brien. The VAR immediately told the referee to hold the restart while he checked the incident (watch here).
VAR decision: No red card.
VAR review: O'Brien grabbed White around the top of the shoulder and threw him to the floor. The assistant spotted this action and advised the referee a yellow card should be shown. That said, the offence happened before the ball went out of play, so the restart really should have been a free kick to Arsenal, rather than a throw-in to Everton.
While O'Brien's action was aggressive, it didn't cross the line for violent conduct for a VAR review.
Verdict: The delay of a minute between the ball going out and the referee showing the yellow card made it appear that the VAR had told the referee to caution O'Brien, which would be against protocol.
After the VAR has told a referee to delay a restart, there isn't any communication with the on-field team about the incident until the sanction is confirmed: no card, yellow or red.
Whenever there's a delay in confirming a sanction during a review, it creates the perception that the VAR has had some kind of role. That will only happen if the referee asks the VAR for confirmation of the identity of the offending player; the sanction is already determined and the referee is seeking to avoid mistaken identity, which is covered in VAR protocol.
Fulham 3-2 Liverpool
Possible penalty: Challenge by Kelleher on Pereira / Van Dijk on Muniz
What happened: The game was only four minutes old when Ibrahima Konaté was caught in possession inside his own area by Andreas Pereira. The Fulham forward helped the ball across the area and was then caught by on-rushing goalkeeper Caoimhín Kelleher. Rodrigo Muniz failed to make full contact with his shot, colliding with Virgil van Dijk. Pereira appealed for a penalty, which referee Chris Kavanagh ignored, and play continued. The passage was checked by the VAR, Matt Donohue.
VAR decision: No penalty.
VAR review: The clash between Van Dijk on Muniz, with the two players occupying the same space, was nothing more than a coming together.
Kelleher's challenge on Pereira, however, showed how referees in all leagues make different judgements with goalkeepers and how they come for the ball.
An unavoidable, natural, coming together in a genuine attempt to play the ball isn't likely to be punished with a penalty, even if the goalkeeper collides into the attacker. The goalkeeper usually has to be reckless to give away a spot kick.
Verdict: While the laws don't distinguish between challenges made inside the area, or give goalkeepers the right to make a careless challenge, in practice they are looked at differently. As goalkeepers are expected to throw themselves at the ball, it's accepted there will be times when there's connection with an opponent after the ball has gone.
For the VAR to get involved, it would have to be clearly reckless -- a challenge in which the keeper had no chance of winning, or in a way that was most likely to cause a foul.
Many may feel Kelleher did cross this line, but it's unlikely to be seen as a missed intervention by the KMI Panel.
Possible red card/penalty: Violent conduct by Van Dijk on Berge
What happened: Fulham won a corner in the 68th minute, with the ball ending up in the hands of Kelleher. However, as the ball came across, Van Dijk was in a tussle with Sander Berge, with the Fulham player left holding his face. As the ball was in play, was there a case for a penalty, and a red card for violent conduct too?
VAR decision: No penalty or red card.
VAR review: Berge had his left arm around around the shoulder of the Liverpool defender, who appeared to throw his own arm and catch his opponent in the face.
Was Van Dijk trying to free himself, or was he fully aware of what he was doing? The law requires "excessive force or brutality against an opponent when not challenging for the ball" for violent conduct.
The VAR could first consider it simply as a foul, and send the referee to the monitor for a penalty. That would, in effect, automatically become a review for a red card as all disciplinary options are open to the referee at the monitor.
Verdict: Van Dijk has been in a number of similar situations throughout the season, always just under the radar of the threshold of a VAR intervention.
It's different than the missed red card for João Pedro on Brentford's Yehor Yarmoliuk in December, when the Brighton & Hove Albion forward clearly threw an elbow.
Van Dijk could have been booked had the referee seen it, but there's unlikely to be a VAR intervention in a case like this with two players involved in simultaneous holding and grappling.
Ipswich 1-2 Wolves
Possible offside: Strand Larsen when scoring
What happened: Wolves scored what proved to be the winning goal in the 84th minute when Jørgen Strand Larsen netted from close range following a pass by Pablo Sarabia. The VAR, Andy Madley, checked for a possible offside by the goal scorer. (watch here)
VAR decision: Goal stands.
VAR review: As we prepare to usher in the new era of semi-automated offside technology (SAOT) on Saturday, was there an error with the application of the old software on a crucial goal that all but sealed Ipswich Town's relegation and secured Wolves' safety?
The offside image looks fairly straightforward, with Strand Larsen shown to be behind the boot of Leif Davis when Sarabia played the pass.
However, all may not be quite what it seems. Davis' foot was in the air, not on the ground, which means there should be a vertical line plotted to the pitch. That pulls the virtual offside line back -- potentially making Strand Larsen offside.
ESPN has been told that the lines were placed in accordance with the normal process, with the VAR having identified both the correct second-last opponent and the relevant body part. Added to that, the vertical line may not always be obvious depending on the height of the boot. Yet it does look like the line was drawn directly to the foot. Perhaps the heavy shadow caused the VAR to miss the raised boot.
It isn't possible to say this was an incorrect decision because plotting the foot to the pitch may still have left Strand Larsen within the tolerance level, and thus onside, but we'll never actually know.
Verdict: Monday night's game between Leicester City and Newcastle United will be the last match with the old software. This should remove any possibility of such human error, with SAOT automatically plotting the players and creating the offside line. The VAR will only need to approve the frame selected by SAOT, and that the offside player is active.
Just as important, it will definitely cut some of the energy-sapping delays we've seen on offside calls recently -- such as the four minutes and 51 seconds taken to disallow Lucas Bergvall's goal for Tottenham against Southampton for an offside against Cristian Romero.
On Thursday, it took almost four minutes to disallow a goal for Chelsea against Tottenham. It was a complicated situation, with many players in close proximity. The offline trials of SAOT showed the decision would have been made two minutes quicker with that technology.
The Premier League says the level of accuracy is the same with both systems, but there must be situations that have resulted in different outcomes when there are so many variables in how a VAR manually plots the players.
Possible red card: DOGSO by Palmer
What happened: Dara O'Shea played a back pass to Alex Palmer in the 36th minute. The ball rolled under the Ipswich goalkeeper's foot and he had to scramble to claw the ball off the line. Palmer prevented a certain goal, so why wasn't he sent off? (watch here)
Verdict: The laws set out that a goalkeeper "cannot be guilty of a handling offence incurring a direct free kick or any related sanction but can be guilty of handling offences that incur an indirect free kick."
So a goalkeeper can concede a free kick (not a penalty) in their own area, but they can't get a yellow or red card.
The only time a goalkeeper can get a card is when they touch the ball a second time on a restart, but this isn't classed as a handling infringement.
Palmer was booked, but for failing to retreat onto his line for the free kick.
Crystal Palace 2-1 Brighton
Possible penalty: Estupiñán challenge on Nketiah
What happened: Eddie Nketiah looked to skip past Pervis Estupiñán in the 69th minute. When the Crystal Palace forward went to ground, referee Anthony Taylor produced a yellow card for simulation. Was there a case for a penalty? The VAR, Craig Pawson, took a look.
VAR decision: No penalty.
VAR review: It wasn't obvious at first, but there was a small amount of contact between Nketiah and Estupiñán. That doesn't mean an attacker can't be booked for a dive if he goes down in a theatrical manner after contact, but it's rare.
Verdict: As the contact was very small, and Nketiah seemed to embellish it, the VAR won't get involved to advise a spot kick. You could argue that Nketiah didn't deserve to be booked, but the VAR can't get involved in this aspect.
The only way a yellow card for simulation can be removed is through a VAR review at the monitor for a penalty.
Possible penalty: DOGSO by Van Hecke
What happened: Jan Paul van Hecke received a second yellow card in the sixth minute of added time when he brought down Daichi Kamada, who was through on goal. Should Van Hecke have received a straight red card for denying an obvious goal-scoring opportunity (DOGSO)?
VAR decision: No DOGSO red card.
VAR review: This appears to be a textbook case of DOGSO, with Kamada certain to have control of the ball and have a direct run on goal when Van Hecke tripped him.
Mats Wieffer, whose poor pass had put Van Hecke in trouble, had no realistic prospect of getting to Kamada before a shot.
Verdict: Should the VAR always intervene to ensure the correct outcome, or leave it alone if it makes no material difference?
Van Hecke should have received a straight red card, but the disciplinary sanction -- a one-match suspension -- would be the same. It would have taken two minutes to send Taylor to the TV monitor to change his decision.
It would have been different for Nketiah and Marc Guéhi, who both received second yellow cards for high-foot challenges. They will both miss next week's trip to Manchester City. Yet if the VAR had intervened to say either of those challenges was serious foul play, that would have resulted in a three-game ban, and they would also miss the fixtures against Newcastle United and AFC Bournemouth.
Tottenham 3-1 Southampton
Possible red card: DOGSO by Ramsdale
What happened: Tottenham Hotspur were on the attack in the 65th minute. Spurs forward Dominic Solanke and Aaron Ramsdale chased a loose ball into the corner of the area, with the Southampton goalkeeper getting to it first. However, he lost control and, as the ball rolled out of the area, he used his hand to bring it back. A free kick was awarded, but referee Michael Salisbury took no disciplinary action. Should the VAR, Graham Scott, have stepped in to advise a red card?
VAR decision: No red card.
VAR review: A goalkeeper handling outside the area isn't automatically sanctionable; it depends upon the context, position and proximity of opposing players.
As the offence happened at such an acute angle to the goal, it would have taken a remarkable first-time shot from Solanke to lift the ball over Ramsdale; while it was a goal-scoring chance, it would have been very low quality in terms of xG. If he'd taken a touch, Solanke would have been closed down by Ramsdale and defender Welington.
The DOGSO qualification applies only to Solanke and not to the team, so the possibility of a pass to a teammate isn't considered.
Verdict: The scoring chance isn't strong enough for a DOGSO red card, so the VAR was right not to intervene.
However, Ramsdale should have been booked for stopping a promising attack. It was a deliberate handball offence to stop an opponent from getting the ball.
Man United 0-0 Man City
Possible penalty: Dias challenge on Garnacho
What happened: Rúben Dias brought down Alejandro Garnacho on the edge of the area in the first minute. Referee John Brooks gave a free kick and the VAR checked the position for a possible penalty.
VAR decision: No penalty.
VAR review: The position is determined by the point of contact of the foul. Even if an attacking player is partly inside the area, if the contact by the opponent is outside, it will be a free kick.
Verdict: The foul took place clearly outside the area, so a free kick was the correct outcome.
Some factual parts of this article include information provided by the Premier League and PGMOL.