27 Aug 2026
How semi-automated offside works in football
Semi-automated offside technology combines cameras, sensors and artificial intelligence to calculate players’ positions at the moment the ball is played. The decision remains the responsibility of the match officials, who review the incident before confirming it.
What is semi-automated offside
It is a video assistant referee support tool, known as SAOT. The system identifies players’ positions and the exact moment the ball is touched. Using this data, it calculates whether an attacker is ahead of the second-last defender when the ball is played.
How the system identifies positions
Cameras installed around the stadium track multiple points on the players’ bodies and the ball. In competitions using the sensor-equipped version, a chip inside the ball records the moment of contact and helps identify which player played the pass. The technology creates a three-dimensional model of the incident within seconds.
Which body parts are included in the calculation
Only body parts that can legally score a goal are considered, such as the head, torso, legs and feet. Arms and hands are excluded. The offside line is drawn from the attacker’s furthest valid point and the position of the second-last defender.
Why the referee still needs to review it
The system flags a possible offence but does not make the final decision on its own. The VAR checks the touch, the players’ identities, the defenders’ positions and whether there was involvement in the play. If the attacker was in an offside position, the video team sends the information to the referee, who can confirm the decision.
How it appears in the broadcast
When offside is confirmed, the broadcast may show a three-dimensional animation with the attacker’s line and the defender’s line. This image helps viewers understand the decision, but it is a graphic reconstruction based on data collected by the cameras and the ball sensor.
The technology’s limitations
Semi-automated offside speeds up decisions in incidents where the position is objective, but it does not eliminate human judgement. Officials must still assess whether the player was involved in the play, challenged an opponent or interfered with the goalkeeper’s line of vision. Camera failures, obscured players and sensor problems may also require a manual review.
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