The offside rule, explained properly.
Offside is the most argued law in football and one of the simplest once you separate three questions: where was the player, when did it matter, and what did the player actually do. This guide walks through each of them.
The position is not the offence
The first thing almost every argument gets wrong is that being in an offside position is not an offence. A player can stand behind the last defender all afternoon without anyone blowing a whistle. The offence only exists if that player becomes involved in play. Position is the precondition; involvement is the foul.
A player is in an offside position when any part of the head, body or feet is in the opponents' half of the pitch (not counting the halfway line itself) and any part of the head, body or feet is closer to the opponents' goal line than both the ball and the second-last opponent. The goalkeeper usually counts as one of the two opponents, which is why people casually say "the last defender" even though the law says second-last opponent.
Which body parts count matters. Hands and arms of every player, including the goalkeeper, are ignored when judging position. For defenders and attackers alike, the arm line is taken from the bottom of the armpit. A striker whose shoulder is ahead of the last defender is offside position; a striker whose outstretched hand is ahead of him is not.
The moment that counts
Position is judged at the moment the ball is played or touched by a teammate — not when the player receives it, and not when the pass was first intended. This is why a run that starts level and finishes five yards clear is perfectly legal, and why a player who was a half-step ahead when the pass left a teammate's foot is offside even if the defenders then run backwards and make him look level.
It is also why the same camera freeze-frame is never quite as clear as it looks on television. The relevant instant is the first contact with the ball by the passer, which video referees now identify frame by frame. A decision can be right to the centimetre and still look wrong to a fan who is watching the receiver's eventual touch rather than the passer's.
What makes a player "involved"
Once a player is in an offside position when a teammate plays the ball, the referee asks whether that player then takes part in active play. The law names three ways:
- Interfering with play — playing or touching the ball passed or touched by a teammate.
- Interfering with an opponent — blocking the goalkeeper's line of sight, challenging an opponent for the ball, clearly attempting to play a ball that is close and so affecting an opponent, or making an obvious action that clearly impacts an opponent's ability to play the ball.
- Gaining an advantage — playing a ball that rebounds or is deflected to him off the goalpost, crossbar or an opponent, or from a deliberate save by an opponent, having been in an offside position.
A player who stands in an offside position but does nothing — lets the ball run through to a teammate who is onside, does not move toward the ball, does not affect the goalkeeper — is not penalised. Many of the most debated goals of the video era come down to whether a decoy runner "affected" a defender, and that call is a judgment of the referee, not a measurement.
Where you cannot be offside
You cannot be penalised for offside if you receive the ball directly from a goal kick, a throw-in or a corner kick. Free kicks and kick-offs are different: kick-offs cannot create offside either, but an attacker can be offside from a free kick, and the position is measured when the kick is taken. You also cannot be offside in your own half, which is why long diagonal balls from deep are rarely stopped for it.
Deflections, saves and "deliberate play"
The subtlest part of the law is what happens when an opponent touches the ball before it reaches the attacker. If the defender makes a deliberate play — a controlled pass, a considered clearance, a trap — the attacker is no longer offside, because the defender chose to play the ball and had the opportunity to do so. If it is a deflection or an unplanned contact, the attacker's offside position from the original pass still stands.
A deliberate save by the goalkeeper (a stop made to prevent a goal) is treated differently again: an attacker who was in an offside position and gets the rebound is judged to have gained an advantage and is offside. Match officials decide between "deliberate play", "deflection" and "save" in real time, which explains most of the inconsistency fans perceive across a season.
Video review and semi-automated technology
The video assistant referee (VAR) is used to check offside in goal situations — whether a goal should stand, and whether an attack was offside before it. Tracking technology now runs in several top competitions: cameras follow a set of body points on each player and combine that with a sensor in the ball to timestamp the kick, so the system can draw the offside line automatically and quickly. The principle is unchanged; the measurement is simply faster and more consistent.
One practical consequence is that decisions are binary and unforgiving. Leaving the line "level" is not a category, and the benefit of the doubt that some fans remember from earlier eras is no longer applied the same way. What stays human is the question of involvement: technology tells you where the body was, but a referee still decides whether a player interfered.
A five-second checklist
- Was the player in the opponents' half?
- At the exact moment the teammate played the ball, was any part of the head, body or feet nearer the goal line than the ball and the second-last opponent?
- If yes: did the ball come directly from a goal kick, throw-in or corner? If so, no offence.
- If not: did the player play the ball, challenge an opponent, or clearly affect one?
- Did an opponent deliberately play the ball in between? If yes, offside resets.
That checklist resolves the great majority of real match situations, and it is exactly the structure behind the daily calls in our game Offsides.
Offsides gives you one real match moment a day: onside or off? You have one call.
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