Premier League to introduce semi-automated offsides on April 12th
Written by
Simon Austin
April 2, 2025
The Premier League will introduce semi-automated offside technology (SAOT) for the first time on Saturday April 12th.
This follows non-live testing of the technology in the Premier League and live operation in the FA Cup fourth round earlier this season. SAOT automates key elements of the offside decision-making process to support the video assistant referee (VAR) and provides more efficient placement of the virtual offside line, using optical player tracking. It also generates virtual graphics to enhance the in-stadium and broadcast experience for fans.
The technology has been developed by Genius Sports, sponsors of the TGG Podcast, in collaboration with the Premier League and PGMOL. The Premier League hopes that, on average, offside decisions will be made more than 30 seconds faster than they currently are.
SAOT will use up to 30 tracking cameras installed in each Premier League stadium – with several capturing footage at 100 frames per second, twice the frame rate of typical broadcast cameras – to help the on-field and video match officials make better and faster offside decisions.
These computer vision cameras, powered by Genius Sports, track the exact movement of the ball, as well as up to 10,000 surface “mesh” data points for each player. SAOT will be used in close offside calls in key moments, such as a penalty, goal or a red card, to either confirm or recommend a change to the referee’s call, as is currently the case with VAR.
To determine these close offside calls, the VAR currently needs to work with Replay Operators to manually determine the “kick-point” for the offside decision and then draw calibrated lines with a crosshair on the relevant defender and attacker, using multiple camera angles. Once the lines and kick-point are determined, an offside or onside decision is generated.
SAOT will suggest a kick point and automatically create offside lines on the second rear-most defender and the relevant attacker, saving significant time in determining whether a player is onside or offside.
There is human input, as the VAR still needs to confirm the decision and that the SAOT system has accurately identified the kick-point and the correct players with the correct part of the body – hence the technology is described as semi-automated.
VAR will also need to determine whether the referee needs to conduct an on-field review for subjective offside calls, such as an attacking player not touching the ball but still interfering with an opponent while in an offside position.
If a player receives a ball in an offside position, the technology will send an alert to the officials in the VAR hub, who will then check the point of contact with the ball and inform the on-field officials.
How the SAOT process will work
Once the SAOT outcome has been reviewed and approved by VAR, a “decision visual” will be automatically generated and distributed to fans on a giant screen in the stadium and shared on the @PLMatchCentre X account.
An offside decision will be shown with a red line and onside with a green line. A white vertical wall will represent the offside line, with a blue “pulse” on the defender’s relevant body part. When an attacker is offside, the part of their body which is offside will appear through the white wall and be outlined in red.
The final image in the virtual replay will be on an angle, off-centre, to provide a clear view of the attacker and defender involved in the offside review and the “pulse” will no longer be displayed.
However, there could still be delays due to “occasions of occlusion of the ball” (if the ball is hidden from the cameras among a group of players), “edge decisions,” or subjective decisions of whether an offside player was interfering with play. That would require intervention from the VAR and possibly the on-field referee in the latter instance.
30 Genius Sports computer vision cameras will be installed at every Premier League stadium
A version of SAOT was used during the 2022 World Cup, but a planned Autumn 2024 introduction to the Premier League never materialised and a new version was developed. The Premier League had also intended to introduce SAOT into top-flight matches after the October or November international breaks this season, only for those plans were delayed.
Premier League chief football officer Tony Scholes said: “The system that we’ve adopted, we believe it to be the best system. We believe it to be the most accurate and the most future-proof system as well.
“I have to confess, given the difficulties that we had over the first few months of the season, I had severe doubts about this but the progress made over the last four to six weeks has been significant.”
“The operation of semi-automated offside technology does not change the integrity of the offside law and doesn’t change the integrity of decision-making. We have got 100% accuracy [on offside after VAR checks] this season, so it won’t improve the accuracy. What it does is make the process more efficient.”
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