For years, some of football’s longest VAR delays came from the smallest margins. A forward’s shoulder, knee or toe might be fractionally beyond the second-last defender, leaving video officials to select the correct frame and place virtual lines by hand. Semi-automated offside technology changes that process. It uses tracking cameras, ball data and artificial intelligence to produce a proposed result within seconds.
That does not mean a computer has replaced the referee. The word “semi-automated” matters. The system handles measuring and line placement, but officials still validate the information and apply the Laws of the Game. As SAOT soccer systems have expanded from major tournaments to domestic leagues, fans have started seeing faster checks and clearer visual explanations.
What Is Semi-Automated Offside Technology?
Semi-automated offside technology, usually shortened to SAOT, is an officiating support system designed to make offside checks faster and more consistent. It combines optical tracking, limb tracking technology, ball tracking and automated alerts to identify when an attacker may have been in an offside position as a teammate played the ball.
The system focuses on two difficult measurements: the exact moment the ball is played and the positions of the relevant body parts of the attacker and defenders. Software then creates a virtual offside line and flags a potential infringement for review.
How SAOT Works Step by Step
1. Cameras Track Players and the Ball
Specialised cameras installed around or beneath the stadium roof continuously follow the players and the ball. FIFA’s system at the 2022 World Cup used 12 tracking cameras and collected up to 29 data points on each player 50 times per second. Other competitions use different configurations, but the principle is similar: building a live three-dimensional map of movement.
The tracked points cover areas such as the feet, knees, shoulders and head. Offside is judged using parts of the head, body or feet that can legally score; hands and arms are excluded. Accurate limb tracking technology is therefore more useful than simply following the centre of a player’s body.
2. The System Finds the Kick Point
An offside position must be assessed at the moment a teammate plays or touches the ball. Selecting that instant can be difficult with ordinary footage, especially during a quick pass or crowded set piece. Some systems use a connected match ball containing a sensor that transmits data hundreds of times per second. Others rely on high-speed optical ball tracking and computer vision.
These offside sensors and tracking tools help identify the first point of contact precisely. The software then matches that kick point with the players’ positions from the same moment.
3. AI Creates a Proposed Decision
Artificial intelligence analyses the data, identifies the relevant attacker and defender, and generates the virtual offside line. When it detects a player receiving the ball from an offside position, it sends an alert to the video match officials.
This is the automated part. The technology completes calculations quickly, but it does not make every football judgement on its own.
4. Match Officials Validate the Result
The VAR team checks the selected kick point and the automatically generated line before the referee is informed. Officials must also decide whether the player in an offside position actually committed an offence by becoming involved in active play.
That distinction is essential. Simply standing offside is not an offence. A player must interfere with play, interfere with an opponent or gain an advantage as defined by Law 11. SAOT supplies accurate positional information, but contextual decisions may still require human interpretation.
5. Fans See a Visual Explanation
After the decision is confirmed, tracking data can be converted into a three-dimensional animation showing the attacker and defender at the moment of the pass. The graphic may be supplied to broadcasters and stadium screens. It explains the ruling rather than making it.
Why SAOT Matters for Modern Football
The biggest benefit is speed. Traditional VAR offside checks can take time because an operator must find the kick point and position the lines correctly. SAOT automates those mechanical steps, allowing officials to concentrate on validating the result and applying the law.
Automated offside calls are based on the same tracking process throughout a competition, reducing differences caused by operators selecting slightly different frames or body points. The system also creates data that can be checked and reproduced.
SAOT has steadily moved into major competitions. FIFA introduced it at the 2022 World Cup, while UEFA has used it in the Champions League since 2022 and combined it with connected-ball technology at Euro 2024. The Premier League began live use on 12 April 2025. At the 2026 World Cup, FIFA used an advanced version that could send alerts for clear positional offsides directly to on-field match officials, helping assistant referees raise the flag sooner.
What SAOT Cannot Do
SAOT does not eliminate judgement, controversy or technical limitations. It can determine positions with great precision, but it cannot independently resolve every question about interference, a defender’s deliberate play or whether an attacker affected an opponent.
Systems also vary between competitions. Some use connected balls, while others rely mainly on optical tracking. Camera numbers, processing methods and fan graphics may differ. If the technology fails, officials can return to established VAR tools and manual virtual offside lines.
There is also a debate about extremely tight decisions. SAOT can measure small margins more reliably, but accuracy does not make every fan comfortable with a goal being ruled out by a few centimetres. The technology applies the law more efficiently; it does not rewrite it.
Frequently Asked Questions
Is semi-automated offside technology fully automatic?
No. It tracks positions, identifies the kick point and creates a proposed line, but video match officials validate the output. The officiating team remains responsible for the final decision.
Does every SAOT system use a sensor inside the ball?
No. Connected-ball technology is used in some FIFA and UEFA competitions, while other systems identify the kick point through optical cameras and computer vision. The setup depends on the competition and provider.
Can SAOT decide whether a player interfered with an opponent?
It can show that a player was in an offside position, but subjective questions about involvement or interference still require officials to interpret Law 11.
Why do assistant referees sometimes delay the flag?
Delaying the flag in a close situation allows play to continue so a legitimate scoring opportunity is not wrongly stopped. Advanced systems can provide quicker alerts for clear positional offsides, but close or complex incidents may still require review.
The Future of Offside Decisions
Semi-automated offside technology is best understood as a faster measuring tool, not a robot referee. Cameras, offside sensors and AI handle the time-consuming geometry, while match officials verify the evidence and decide how the law applies. As the technology improves, alerts may arrive sooner and fan graphics may become more realistic, but human oversight will remain central.
For supporters, the practical difference is straightforward: fewer lengthy line-drawing delays, more consistent measurements and clearer explanations. SAOT will not end every argument about offside, but it is making one of football’s most technical decisions quicker and easier to understand.