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: Possible handball penalties against Marc Cucurella and Kieran Trippier, plus why Tottenham Hotspur didn't get a penalty at Fulham and Brighton & Hove Albion's disallowed goal at Manchester City.
Arsenal 1-0 Chelsea
Possible penalty: Handball by Cucurella
What happened: In the 12th minute, Thomas Partey attempted to play Jurriën Timber in down the right with Marc Cucurella giving chase. As the Chelsea defender went to ground under pressure from Timber the ball appeared to come off his arm, but referee Chris Kavanagh allowed play to continue. It was checked by the VAR, Jarred Gillett. (watch here)
VAR decision: No penalty.
VAR review: When is an arm in an expected position, and when does it cross over into a deliberate act?
The VAR will look at a player's natural movement as part of the passage of play -- so how he is running, jumping or challenging -- rather than just the handball. It helps to paint a clearer picture of how the player's arms are moving as he gets to the ball. Does this change, or is it consistent?
Last weekend, Southampton defender Yukinari Sugawara conceded a penalty at Liverpool. His arm was close to his body but there was a clear and deliberate movement of the elbow onto the ball to prevent Luis Díaz from getting to it. That was an obvious intervention for the VAR, Matt Donohue.
The Cucurella incident wasn't as clear, and indeed there was a question about the contact being too high on the arm for handball. But there was also a case that the Spain international was intending to chest the ball, realised it was going wide of his body so held his arm in the position so it wouldn't allow Timber a free run into the area.
Verdict: There will always be edge cases where determining intent, or indeed point of contact, is difficult where there isn't obvious movement of the arm, like we saw with Sugawara.
Indeed, in the Carabao Cup final on Sunday there was a claim against Kieran Trippier. Again it was Liverpool forward Díaz involved as he chased a long ball over the top. After the ball bounced it touched the hand of the Newcastle United player, taking it away from Díaz. Referee John Brooks ignored the penalty appeals from Daz and Andrew Robertson.
Trippier was running and had both arms out for balance, so that's justifiable. But was there a small movement of the arm toward the ball?
With a more lenient approach to handball in the Premier League, we wouldn't expect to see a penalty awarded for either of these situations.
Possible red card: Challenge by Partey on Neto
What happened: In the 17th minute, Partey challenged Pedro Neto for a loose ball but caught the Chelsea player above the boot. No card was shown, but was there a case for a red card?
VAR decision: No red card.
VAR review: The referee had allowed play to continue to the point of the Partey challenge, and brought it back for an earlier foul.
Contact was high as Partey stretched to get to the ball, but it was only glancing and with no force.
Verdict: Partey should have received a yellow card for a reckless challenge, but it didn't reach the threshold for a red card.
Even though the referee had awarded the previous foul, Partey was still sanctionable.
Possible red card: Challenge by Fofana on Rice
What happened: Declan Rice won a free kick in the 23rd minute after being fouled by Wesley Fofana. When the Arsenal midfielder was on the ground, Fofana tried to get to the ball and seemed to catch Rice on the thigh. The referee took no disciplinary action, but was there a case for a red card?
VAR decision: No red card.
VAR review: There's little doubt Fofana knew what he was doing, so he was fortunate to escape without a yellow card.
Verdict: There wasn't any force involved to constitute serious foul play, so the VAR was correct not to get involved.
Fulham 2-0 Tottenham
Possible penalty: Challenge by Spence on Jiménez
What happened: The match was in the 23rd minute when Alex Iwobi swung a cross into the award toward Raúl Jiménez. The Mexico international jumped to head the ball, but felt a push in the back from Djed Spence and went to ground asking for a penalty. Referee Andy Madley ignored the claims and play continued.
VAR decision: No penalty.
VAR review: One of the key considerations on all VAR reviews is the way a player goes to ground, and whether that matches the level of contact from the opponent.
Spence had both hands on Jiménez's back, but there didn't seem to be a push. The leap forward by Jiménez seems to come after Spence's hands have come off his back; the VAR would argue that the striker was way too theatrical for it to be natural impact.
Verdict: It's where attackers are often caught in the middle -- if they don't make sure the contact is noticed, the referee won't give it; but at the same time, if they make too much of it the VAR won't step in.
This isn't going to given as a spot kick in the Premier League.
But then there's the numerous soft penalties given on the field with minimal contact that the VAR won't step in to correct it. You can understand why this gives the impression of inconsistency in final outcomes.
Possible penalty: Challenge by Bassey on Bergvall
What happened: It was 1-0 to Fulham in the 85th minute when Lucas Bergvall moved into the penalty area and tried to go past Calvin Bassey. The Tottenham Hotspur player went to ground and turned to referee Andy Madley looking for a penalty, but he allowed play to continue with the ball in the gloves of goalkeeper Bernd Leno. It was checked by the VAR, Paul Tierney.
VAR decision: No penalty.
VAR review: One side of the argument says Bassey put his left leg across the front of Bergvall, which prevented the Sweden international from being able to continue his run into the area.
The other is that it was 50-50 for either player to get to the ball first, and legs collided in doing so.
Was this a missed penalty, or were Spurs a victim of the high threshold in the Premier League?
Verdict: The Premier League's Key Match Incidents Panel has logged only three VAR errors for missed penalties this season, and they have all been for holding offenses rather than tackles.
The KMI panel has, though, logged 12 penalties that should have been given by the referee, but didn't reach the threshold for a VAR intervention. Can we add this to the list?
Indeed, in the most recent judgements of the KMI panel it was noted that Brentford should have been given a spot kick by the referee for a challenge by Leicester City's Woyo Coulibaly on Kevin Schade -- but it didn't cross the threshold for VAR.
The same ruling was made on the penalty Spurs wanted at Ipswich Town for Dara O'Shea's challenge on Kevin Danso.
This might be another close vote, but it looked more of a penalty because Bergvall appeared the favorite to get to the ball and was prevented from doing so.
Liverpool 1-2 Newcastle (Carabao Cup final)
Possible goal: No Guimarães offside
What happened: Newcastle thought they had doubled their lead in the 59th minute when Alexander Isak scored from close range. However, the assistant raised his flag to disallow it for offside against Bruno Guimarães.
VAR decision: No goal
VAR review: As Dan Burn headed toward goal, Guimarães was offside and in front of goalkeeper Caoimhín Kelleher.
Kelleher had to go past Guimarães to get to the ball, which meant he had to be influenced by the presence of the Newcastle United midfielder.
Verdict: A correct decision by the on-field officials, and we'd expect the VAR to get involved if the goal had been given. Kelleher was unsighted and could only parry the ball to Isak, so Guimarães had to have impacted the outcome.
Man City 2-2 Brighton
Possible disallowed goal overturn: Mitoma foul on Ortega
What happened: Brighton & Hove Albion thought they had taken the lead after only six minutes when Kaoru Mitoma put the ball into the back of the net. However, referee Simon Hooper disallowed the goal for foul on Stefan Ortega. (watch here)
VAR decision: No goal.
VAR review: Mitoma had seen his initial effort saved by Ortega, before the ball was forced in.
However, Ortega had both gloves on the ball, and the law states that a goalkeeper cannot be challenged when "the ball is between the hands."
Verdict: Even if the goal had been allowed on the field it would have been disallowed as, by law, the goalkeeper had the ball under his control.
The match saw James Bell become the latest Select Group 2 (Championship) referee to step into a VAR-only role in the Premier League, following Alex Chilowicz and Matt Donohue. It's part of PGMOL's move to create a pool of VAR specialists, with assistant referees Neil Davies and Nick Hopton also having stepped up into the lead position this season, to place less workload on the top-flight referees.
Possible penalty overturn: Foul by Webster on Marmoush
What happened: Manchester City were awarded a penalty in the ninth minute when Adam Webster was ruled to have brought down Omar Marmoush. It was checked by the VAR.
VAR decision: Penalty stands, scored by Erling Haaland.
VAR review: Webster slid in to make a block, but Marmoush checked inside rather than took a shot. As he did so, Webster caught the forward's left boot with his trailing leg and brought him down.
Verdict: Some Brighton players complained, but Webster certainly didn't. Marmoush was clearly clipped and it was a penalty.
Everton 1-1 West Ham
Possible penalty overturn: Kilman foul on Beto
What happened: Everton were awarded a penalty right at the end of the first half. Beto had attempted to get a shot off and went to ground, with referee Darren Bond pointing to the spot. It was checked by the VAR, Chris Kavanagh. (watch here)
VAR decision: Penalty cancelled.
VAR review: The referee gave the penalty against Max Kilman, who was close behind and was deemed to have impeded the striker in the act of shooting.
Replays clearly showed that Beto had kicked the ground when trying to shoot and there had been no challenge by Kilman.
Verdict: A slightly odd situation, as no West Ham player seemed to make too much of the penalty award, but there was no foul challenge, and it was a correct VAR intervention.
Similarly, Ipswich Town had a penalty cancelled against Everton in October when Jack Clarke caught Dwight McNeil with his back lift in the act of shooting.
It's the third penalty Everton have had overturned through VAR this season.
Bournemouth 1-2 Brentford
Possible red card: Challenge by Semenyo on Lewis-Potter
What happened: In the 75th minute, Antoine Semenyo was shown a yellow card after catching Keane Lewis-Potter in the side of the face with his arm. Was there a case for a red card?
VAR decision: No red card.
VAR review: Semenyo seemed to have a glance over his shoulder, so he was aware that the Brentford midfielder was in close proximity.
For this to cross from a reckless act to violent conduct, there would have to be a clear degree of brutality.
Verdict: The elbow wasn't raised or thrown at the opponent, so a yellow card was an acceptable outcome.
Some factual parts of this article include information provided by the Premier League and PGMOL.