VAR can spot an incident and still do nothing about it.

That is one of the biggest sources of confusion in modern football. Supporters see a replay showing something went wrong, assume VAR must be able to correct it, and then watch play continue.

But VAR is not a second referee with permission to fix every mistake. The protocol limits both what can be reviewed and how wrong the original decision has to be before VAR should intervene.

That distinction explains a surprising amount of the controversy around the system.

For the broader picture of how the technology works, start with VarVote's guide to VAR in football. Here, the focus is narrower: when is VAR actually allowed to step in?

The basic rule: VAR is for match-changing decisions

Under the current IFAB protocol, VAR can assist the referee in a defined set of situations.

The main categories are:

VAR is not designed to correct every foul, throw-in, free-kick or yellow card during a match.

That matters because a decision can be wrong without being reviewable.

It also means the phrase often heard during broadcasts, 'VAR checked it', does not mean VAR had the power to change everything it saw in the build-up.

Goal or no goal

Every potential or actual goal is checked by VAR.

The check can include offences by the attacking team during the attacking phase that led to the goal, including offside, handball and fouls. VAR can also check whether the ball went out of play before the goal and whether the ball actually crossed the goal line.

This is why the celebration sometimes comes before the real argument. The ball can be in the net, the referee can award the goal, and VAR can then identify an earlier offence that changes the outcome.

But even here, VAR cannot simply travel backwards through the match indefinitely looking for something that was wrong.

The limits of that process became particularly visible in VarVote's 1 September Weekend Review. Nottingham Forest's attack against Liverpool began with a disputed throw-in. VAR could check the later penalty incident, but it could not go back and correct the throw-in itself.

That is an important distinction: something can matter to the attack without automatically being something VAR is allowed to review.

Penalty or no penalty

Penalty decisions are one of VAR's central responsibilities.

VAR can intervene when a penalty has been incorrectly awarded or when a penalty offence has been missed. It can also correct factual elements surrounding the decision, such as whether the offence happened inside or outside the penalty area.

This is where the difference between a factual error and a judgement call becomes important.

If replay clearly shows that contact occurred outside the penalty area, the location can be corrected. Deciding whether the contact was actually enough to constitute a foul may require a much higher threshold for intervention.

That exact tension has appeared repeatedly in VarVote's match coverage. In the 1 September Weekend Review, one Arsenal penalty was overturned because the foul was clearly outside the box, while another disputed challenge remained untouched because the question was whether the contact itself justified a penalty.

Same technology. Very different type of decision.

What does 'clear and obvious' really mean?

This is the phrase that sits at the centre of almost every VAR argument.

For most subjective decisions, the question is not simply:

Was the referee wrong?

The question is closer to:

Was the referee clearly and obviously wrong?

That creates a deliberate gap between a decision another referee might disagree with and a decision VAR should overturn.

The original on-field decision matters. VAR is supposed to intervene when the video shows a clear error or when a serious incident has been missed, not simply because the video official would personally have made a different judgement.

This is also why two apparently similar incidents can produce different outcomes without either automatically proving inconsistency.

The intervention threshold itself has become one of the biggest issues in European football. Serie A's early-season experiment with a higher VAR threshold produced 18 matches without a single on-field review. The referees were still being supported by VAR, but the bar for asking them to reconsider subjective decisions had clearly been set high.

That approach creates faster matches and fewer interruptions. It also means some debatable decisions are deliberately allowed to stand.

A VAR check is not the same as a VAR review

These terms are often mixed together, but they describe different stages.

VAR automatically checks potential match-changing incidents. Most of those checks happen quietly in the background.

If the footage does not show a probable clear and obvious error or serious missed incident, the game continues. The referee may never go near the monitor.

A review happens when the VAR identifies something that may justify changing the decision and recommends that the referee reconsider it, or when the referee believes a serious incident may have been missed.

For subjective decisions, the referee will normally conduct an on-field review, watching the footage at the pitchside monitor before making the final decision.

That distinction is easy to see in VarVote's 25 August Weekend Review. The weekend included incidents where VAR changed the original decision, incidents where it checked and supported the referee, and controversial moments where no intervention followed at all.

All three can involve VAR. They are not the same process.

Can VAR intervene on a red card?

Yes, but the rules are more specific than simply 'VAR checks cards'.

VAR can intervene in potential direct red-card situations involving incidents such as serious foul play, violent conduct or denying an obvious goalscoring opportunity.

The current protocol also allows intervention when a second caution has clearly been shown incorrectly and therefore results in a player being sent off.

That change has an important limit.

VAR cannot search for a yellow-card offence that the referee completely missed and recommend a second yellow simply because the player already has one. The protocol allows VAR to correct a clearly incorrect second caution that was actually given, not to referee every possible second-yellow incident from the video room.

That distinction is easy to miss, but it is significant.

Mistaken identity

VAR can also intervene when the referee has punished the wrong player.

If one player commits an offence and the referee mistakenly shows a yellow or red card to a teammate from the same team, VAR can help identify the correct offender.

This does not give VAR a general power to reassess the offence itself. The purpose of the intervention is to correct the identity of the player being disciplined, unless the incident independently falls within another reviewable category such as a penalty or red card.

Can VAR correct a corner kick?

This is one of the newer additions to the protocol.

Competitions can now choose to allow VAR assistance when a corner kick has been clearly incorrectly awarded, provided the decision can be corrected immediately without delaying the restart.

That does not mean every corner becomes a lengthy video review.

The intention is the opposite. Where the video official can immediately see that the ball clearly came off the attacking team rather than the defender, the mistake can be corrected before the corner is taken.

It is also a competition option, so supporters should not assume it is being used in every competition simply because it exists in the Laws.

Can VAR go back before the ball is in play?

There is another important development here, but it should not be confused with the standard protocol.

IFAB is running a trial concerning attacking-team offences that happen before the ball is in play at certain attacking restarts, such as corners and free-kicks.

The trial is designed for situations where an offence before the restart has a direct and immediate impact on a subsequent goal, penalty or disciplinary decision.

Because this is a trial rather than a universal VAR rule, whether it applies depends on the competition.

That is another reason blanket statements such as 'VAR can never go back before the corner' or 'VAR can always check the push before the kick' can both be misleading. The competition and the protocol being used matter.

What VAR still cannot fix

The easiest way to understand the system may be to look at what falls outside it.

VAR cannot normally intervene simply because:

Even when one of those decisions eventually contributes to a goal or penalty, the protocol still has boundaries on what can be reviewed and how far the process can go back.

That can feel unsatisfactory. It is also intentional.

A system that could search backwards through every possession for every possible error would turn football into something very different.

Why the arguments will not disappear

VAR can answer factual questions extremely well.

Was the player offside? Was the foul inside the area? Did the ball cross the line? Did the defender touch the ball last?

The harder questions are still football questions.

Was the contact enough for a foul? Was the challenge reckless or serious foul play? Did an attacker genuinely interfere with an opponent? Was the referee's judgement merely debatable, or clearly wrong?

Video does not remove those decisions. It gives officials more information with which to make them.

And that is where the modern VAR debate increasingly sits.

The biggest argument is no longer simply whether technology can identify mistakes. It clearly can.

The argument is which mistakes football actually wants VAR to correct.

That is why the intervention threshold matters as much as the cameras themselves.

For examples of how those boundaries play out in real matches, browse VarVote's recent VAR decisions or read the latest VarVote analysis and reviews.