Semi-automated offside technology is a support tool that automates the positional part of an offside review for the video assistant referee, tracking a player's body against the last defender and the moment the ball is played rather than leaving a human to draw the line by hand. The Premier League introduced its version on Saturday, April 12, 2025, describing it as a system that "automates key elements of the offside decision-making process for the video assistant referee (VAR)," while the final call on whether a flagged position actually amounts to an offence still rests with the on-field officials.
What actually counts as an offside offence?
Technology only ever answers one part of a two-part question, and the underlying law has not changed to accommodate it. Under Law 11, a player is in an offside position if "any part of the head, body or feet is in the opponents' half" and nearer to the opponents' goal line "than both the ball and the second-last opponent," with hands and arms excluded from the calculation and any player level with the second-last defender specifically exempted. Being in that position is not itself an offence. A player is only penalized once "becoming involved in active play," which the Laws define as playing or touching the ball, interfering with an opponent's ability to play it — including obstructing a line of vision or making "an obvious action which clearly impacts" a defender's chance to play the ball — or gaining an advantage from a ball that rebounds off a post, crossbar, official, or opponent. Receiving the ball directly from a goal kick, throw-in, or corner is never an offence, and nor is receiving it after an opponent has deliberately played it. Semi-automated systems resolve the positional half of this test; the "active play" half remains, as it always has, a judgment call for the video assistant referee.
How does the tracking system actually work?
The Premier League's implementation relies on a bank of stadium cameras — up to 30 of them, several capturing footage at 100 frames per second — trained on the pitch to build a continuous positional record of every player. According to the league, the system generates "up to 10,000 surface data points per player," from which it constructs a virtual skeletal model precise enough to establish the exact placement of a shoulder, knee, or trailing foot at the instant the ball is struck. The technology cross-references that positional data against the moment of the pass to flag potentially offside positions automatically to the video assistant referee and a dedicated SAOT operator, rather than requiring an operator to manually select the relevant frame and drag a virtual line across it, which was the standard VAR method before automation arrived.
Why is a human still part of the decision?
The system is described as semi-automated rather than fully automated for a specific reason: three judgment steps still require sign-off from the video assistant referee before an offside line is broadcast. The VAR must confirm that the technology has identified the correct kick point, the correct pair of players being compared, and the correct body parts being measured on each of them. Only once those three elements are verified does the automated line appear on screen. Subjective questions — whether a player in an offside position genuinely interfered with an opponent's ability to play the ball, for instance, rather than simply standing near the passage of play — are not something the cameras can resolve at all, and continue to be decided by the video assistant referee applying Law 11's active-play test described above.
How has the technology changed since it first appeared?
Semi-automated offside review was not built for the Premier League; it arrived there as a more advanced version of a system first used at a men's World Cup. Earlier descriptions of the technology, tied to its rollout across Serie A, La Liga, and the Champions League, described a model built around roughly 29 tracked points on each player's body, with ball-sensor data supplementing camera tracking to pin down the moment of contact. The version the Premier League brought in for the 2024-25 season, following a period of non-live testing and live use in FA Cup fixtures, works from a denser positional model — the league's own figure of up to 10,000 surface data points per player — built to render a fuller body outline than the earlier points-based skeleton, which matters most in the tightest calls, where a misjudged elbow or trailing studs is the entire margin.
Does the automation actually make offside calls more accurate?
The Premier League has reported that offside calls have been adjudged "100 per cent correct" since the system's introduction, though that is the league's own retrospective review of its officials' work rather than an independent audit, and the sourcing chain for that claim runs no further than the competition organizer itself. What is more straightforwardly verifiable is the speed gain: the league has said the system cuts the average time needed to resolve a close offside review by roughly 30 seconds compared with the manual line-drawing method it replaced. That figure addresses process, not correctness — the automation removes the manual, error-prone step of selecting a frame and drawing a line by hand, but it cannot adjudicate the active-play judgment that still decides whether a correctly identified offside position was actually an offence.
Frequently asked questions
- Does semi-automated offside technology decide offside on its own? No. It automates the positional measurement — where a player's body was relative to the ball and the last defender — but a video assistant referee must confirm the kick point, players, and body parts before any line is shown, and still makes the separate judgment on whether the position was an offence.
- When did the Premier League start using it? The league introduced semi-automated offside technology on Saturday, April 12, 2025, after a season of non-live testing and live trials in FA Cup matches.
- Can a player be offside without touching the ball? Yes. Under Law 11, an offside offence can also arise from interfering with an opponent's ability to play the ball or gaining an advantage from a deflection, without the offside player ever touching it themselves.
- Is a player offside if level with the last defender? No. The Laws of the Game specifically exempt a player who is level with the second-last opponent, or with the last two opponents, from being in an offside position.
For a related tactics perspective, read How the video assistant referee actually reviews an offside call.