Offside: Active Involvement

IFAB defines active involvement in three ways. First, a player who directly receives the ball from a teammate while in an offside position is offside. Second, a player who interferes with an opponent — by blocking their line of sight or movement even without touching the ball — may be penalised. Third, a player who gains an advantage from being in an offside position, such as playing a ball that rebounds off the post or goalkeeper while they were originally offside, is also penalised. This third category is the most contentious.

If a player is in an offside position but does not become involved in the play — they run away from the ball, stand still while a teammate plays the ball on the other side of the pitch, or simply have no influence on the action — they are "passively offside" and the game continues. Referees and assistant referees must make near-instantaneous judgments about whether a player is likely to become active before flagging. The instruction since the VAR era is to delay the flag to allow VAR review.

VAR has transformed offside decisions from judgment calls into semi-automated measurements. Automated offside technology (AOT), used at the 2022 Qatar World Cup, can detect whether a shoulder, knee, or armpit is fractionally beyond the last defender. This has produced both more accurate decisions and significant controversy — goals disallowed for an outstretched armpit or a toe being a centimetre beyond the defensive line. Critics argue the technology has removed the benefit of the doubt that the original law intended to provide to attackers.

Several famous goals were ruled out for offside active involvement. In the 2018 World Cup, France's Antoine Griezmann was initially flagged before VAR confirmed the move was legitimate. Manchester City's Gabriel Jesus had a goal controversially disallowed in the 2019 EFL Cup final for offside — later judged as marginal but within the law's bounds. These decisions have spurred ongoing debate about whether the law should be reformed to reintroduce clear daylight as the offside standard rather than millimetre margins.