Leeds United could be embroiled in VAR controversy this season.
The technology will be used if the Whites are drawn away to a Premier League team in the Carabao Cup or FA Cup.
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Video assistant referees support the decision-making process of referees. They are only used in the four game-changing situations and provide minimum interference with maximum benefit.
VAR only intervenes in the course of a match when the officials have made a 'clear and obvious error' in one of four key areas. They are:
A close offside decision is the most common reason for VAR being consulted after a goal has been scored, but shirt-pulling and other infringements can cause goals to be chalked off.
The most subjective and potentially problematic area. Penalties can be awarded or rescinded using VAR if there has been a 'clear and obvious error' in the original decision.
Straight red cards
Violent conduct and dangerous tackles can be penalised using VAR. Second-yellow cards cannot.
If the referee sends off the wrong player that injustice can be repaired.