Semi-Automated Offside in the Premier League: How It Works

There is a particular kind of pause in modern football that didn’t exist before. A goal is scored, but the reaction is slightly delayed. Players hesitate before celebrating fully. The crowd waits, not quite sure whether the moment will stand.

That hesitation has become part of the game. Semi-automated offside technology is an attempt to reduce it, not by removing VAR, but by changing how offside decisions are actually constructed.

At its simplest, semi-automated offside technology (SAOT) is a support system. It works alongside VAR to verify offside decisions, particularly in situations where the margins are too fine to judge confidently in real time. The Premier League introduced it to improve the speed, efficiency and consistency of decisions, rather than to claim a completely new level of accuracy.

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The Premier League introduced it to improve the speed, efficiency and consistency of decisions, rather than to claim a completely new level of accuracy.

To understand the impact of semi-automated offside technology on the modern game, it is helpful to look at the specific technical requirements and the performance data recorded since its implementation.

The following data points highlight how the system operates and its effect on a match-day :

• Semi-automated offside technology (SAOT) was introduced in the Premier League in April 2025. (Premier League)
• The system uses 30 cameras installed in each stadium to track player movements and the ball. (Premier League / Genius Sports)
• Cameras operate at up to 100 frames per second, providing greater precision than standard broadcast footage. (Premier League Technology Overview)
• SAOT tracks multiple data points per player’s body (including limbs and torso) to create a 3D model for offside decisions. (FIFA / Premier League Technology Reports)
• The system reduces reliance on manual line drawing, which was previously required in VAR decisions. (PGMOL)
• VAR decision times for offside decreased from an average of 64 seconds to 39 seconds after implementation. (Premier League)
• The Premier League reported 100% offside decision accuracy during the 2024–25 season using SAOT-supported processes. (Premier League)
• A 5 cm tolerance margin is applied in offside decisions to avoid marginal “toenail” calls. (Premier League Officiating Guidelines)
• SAOT was first used globally at the 2022 FIFA World Cup in Qatar. (FIFA)
• The system operates as semi-automated, meaning decisions are still verified by human VAR officials rather than being fully automated. (PGMOL / FIFA)
• The technology is delivered through a partnership between the Premier League, PGMOL and Genius Sports, which became the league’s official data partner in 2019. (Premier League / Genius Sports)
• During trials, an FA Cup match saw a delay of around 8 minutes due to system issues, highlighting potential operational challenges. (BBC Sport)
• SAOT processes thousands of positional data points per second to reconstruct offside situations in real time. (FIFA Technology Reports)
• The system generates a visual 3D offside graphic, which is shown to fans to explain decisions more clearly. (FIFA / Premier League)

From Interpretation to Verification

Before SAOT, offside decisions relied on a layered process that was both technical and interpretive. VAR officials had to identify the exact moment the ball was played, then compare the positions of attacker and defender at that instant.

In theory, this is a simple sequence. In practice, it is more like trying to pause a video at the exact moment a foot makes contact with the ball. One frame too early or too late can shift the outcome.

Officials would draw lines across the pitch using different camera angles. These lines represented a carefully constructed interpretation of reality. They were precise, but they still depended on human judgement at key moments.

The introduction of SAOT changes the nature of that task. Instead of building the decision manually, the system generates it from tracked data. The role of the official becomes one of verification rather than construction.

A System That Tracks the Game in Detail

The technology itself is built around a network of cameras and data processing. In the Premier League, 30 cameras are positioned around each stadium. These cameras capture footage at up to 100 frames per second, which is significantly higher than standard broadcast footage.

That increase in detail matters because it allows the system to identify the moment the ball is played with much greater precision.

At the same time, the system tracks thousands of data points on each player’s body. These include visible reference points such as knees, shoulders, arms and head. Each player is effectively mapped in three dimensions, creating a moving digital model that reflects their exact positioning.

The result is a reconstruction of the moment that no longer depends on a single camera angle or a manually selected frame. The system identifies the relevant body part, determines its position relative to the defender, and produces a visual output that shows whether an offside has occurred.

This output is then reviewed by VAR. The decision is not fully automated. The technology produces the evidence, but a human still confirms it.

Speed, Not Just Accuracy

The Premier League has been careful in how it describes the benefits of SAOT. It does not claim that the technology makes decisions more accurate in a strict sense. Instead, it emphasises improvements in speed and consistency.

During the 2024 to 2025 season, the average VAR delay reduced from 64 seconds to 39 seconds. That is a noticeable difference in a live match, even if it does not remove the pause entirely.

The Premier League reported 100 percent offside accuracy during that season. Whether that reflects the system itself or the overall process is harder to separate.

The Context Behind the Change

The move toward SAOT did not happen in isolation. It followed a series of high-profile VAR errors that undermined confidence in the process.

On one matchday, Brighton had a goal incorrectly ruled out after lines were drawn against the wrong Crystal Palace defender. In another match, an offside player in the build-up to a Brentford goal against Arsenal was not identified at all.

These were not marginal decisions. They were clear errors within a system that was supposed to reduce them.

SAOT is partly a response to those moments. By automating the identification of positions and timings, it removes some of the points where human error can enter the process.

That does not mean mistakes disappear entirely. It changes where they are likely to occur.

When the Technology Doesn’t Work

The introduction of SAOT has not been without its own complications. During its trial phase, there was a moment that captured some of the tension around its use.

In an FA Cup match between Bournemouth and Wolverhampton Wanderers, a prolonged stoppage of around eight minutes followed issues with the system. Officials struggled to switch between the AI platform and the match feed. The delay was long enough for frustration to build inside the stadium.

The reaction from the crowd was immediate and vocal. It was not directed at a specific decision, but at the interruption itself.

That moment highlighted something important. Introducing technology does not just change decisions. It changes the rhythm of the game. When it works, the process becomes smoother. When it doesn’t, the disruption becomes more visible than before.

The Role of Tolerance

One of the more subtle aspects of SAOT in the Premier League is the continued use of a tolerance level. A margin of five centimetres is applied in offside decisions, effectively giving the benefit of the doubt to the attacker in extremely close situations.

This is sometimes referred to as protection against “toenail” decisions, where a minimal difference in position leads to a goal being disallowed.

Other leagues using SAOT have moved away from this kind of buffer. The Premier League has chosen to retain it.

That decision suggests a certain caution. Even with highly detailed tracking data, there is still an acknowledgement that absolute precision may not always produce outcomes that feel fair within the context of the game.

It also reflects an understanding that football is not only about measurement. It is also about interpretation.

Development and Ownership

SAOT in the Premier League has been developed through a partnership involving the league itself, the Professional Game Match Officials Limited (PGMOL), and Genius Sports.

This collaboration began in 2019, with Genius Sports acting as the official data partner for Football DataCo. The system builds on existing data infrastructure, including tools designed to enhance the viewing experience for fans.

One example is the Data Zone feature available on certain broadcasts, which allows viewers to access detailed statistics and tracking information during matches.

In that sense, SAOT is not just an officiating tool. It sits within a broader ecosystem of data and analysis that is becoming increasingly central to how football is presented and understood.

Reactions From Within the Game

Those working within football have generally framed SAOT as a practical improvement rather than a transformation.

Howard Webb, Chief Refereeing Officer at PGMOL has said the system does not change the nature of offside decisions, but it reduces the time required to reach them.

That emphasis reflects a broader view within officiating. The belief is that offside decisions were already largely accurate, but the process used to arrive at them could be improved.

Outside that group, reactions have been more mixed. Some managers and commentators continue to question the broader impact of VAR on the game, regardless of how individual decisions are made.

A Technology Still Finding Its Place

SAOT has only been in use in the Premier League since April 2025. In practical terms, that is a very short period.

The system has already changed how offside decisions are produced and presented. It has reduced delays and standardised parts of the process that were previously open to interpretation.

At the same time, it has not resolved every concern around officiating. It still relies on human verification. It still operates within a framework that includes subjective judgement.

What it offers is a different balance. Less emphasis on manual construction, more reliance on automated detection, and a clearer visual output that can be shared with players and fans.

FAQ

What is a semi-automated system?

A semi-automated system combines technology with human input. The system performs key tasks using data and automation, but a person still reviews or confirms the outcome rather than leaving decisions entirely to machines.

What is semi-automated technology?

Semi-automated technology uses advanced tools, such as cameras and data tracking, to generate decisions or outputs. However, a human remains involved to verify or oversee the final result.

What is the difference between automated and semi-automated?

Automated systems make decisions entirely without human input. Semi-automated systems generate results using technology but still require human verification or confirmation before a final decision is made.

What is semi-automated offside in England?

Semi-automated offside technology in England is a system used in the Premier League to support VAR. It tracks player positions and the ball using cameras and data, generates offside decisions, and allows officials to verify them for faster, more consistent outcomes.