What is Offside?

Definition and Purpose

Have you ever watched a football match and the ref whistles while one of the players is ahead of the defending team? That’s because the offence broke one of the most common rules that football players break in football matches. It aims to prevent attacking players from lingering in front of the opponent’s goal, allowing them to enter the space behind the last defensive player only after the ball is played.

This rule is central to how teams attack and defend, with defensive lines maintaining shape and moving collectively, knowing that attackers cannot settle behind the line until the ball is in play. The offside rule promotes possession-based football, allowing defenses to move higher up the pitch. For attackers, timing forward runs is crucial, as being level or behind the defensive line at the time of the pass is essential, rewarding pace, precision, and skill. Without the offside rule, football could devolve into a strategy of overwhelming the opponent’s area with numerous attacking players and spamming long balls, fundamentally altering the nature of the game.

Offside Position

A player assumes an “offside position” if they find themselves in the opposing team’s half of the field and are “closer to the opponents’ goal line than both the ball and the second-last opponent.” Simply put, a player is in an offside position if two conditions are met:

  1. Any part of the player’s head, body, or feet is in the opponents’ half of the field (excluding the halfway line).
  2. Any part of the player’s head, body, or feet is closer to the opponents’ goal line than both the ball and the second-last opponent.

While the goalkeeper is included as an opponent in the second condition, it is not obligatory for the last opponent to be the goalkeeper.

Active Involvement in Play

A player positioned in an offside stance when the ball is touched or played by a teammate is penalized for an offside offence if, in the referee’s opinion, they actively engage in play by:

  • Interfering with play by “playing or touching the ball passed or touched by a team-mate.”
  • Interfering with an opponent, which includes preventing an opponent from playing the ball by obstructing their line of vision, challenging for the ball, attempting to play a close ball that impacts an opponent, or making an obvious action that affects an opponent’s ability to play the ball.
  • Gaining an advantage by playing the ball or interfering with an opponent when the ball has rebounded or been deflected off the goalpost, crossbar, match official, or an opponent, or when it has been deliberately saved by any opponent.

Determining whether a player is “involved in active play” can be intricate. FIFA introduced guidelines in 2003 and updated Law 11 in July 2005 to clarify phrases like “interfering with play” and “gaining an advantage.” In 2015, IFAB issued additional guidance to define movements a player in an offside position could make without interfering with an opponent, which is now included in the main body of the law. The guidance addresses conditions under “Interfering with an opponent” and clarifies the meaning of a save in the context of a ball deliberately saved by any opponent.

Offside Decision Process

Officiating in football involves nuanced signals from assistant referees, particularly in indicating the location of an offside offense. When signaling that the offside occurred in the middle of the pitch, the assistant referee points the flag upwards at a 45-degree angle on the far side and downwards at a 45-degree angle near the assistant referee.

In implementing this rule, the referee heavily relies on the assistant referee, who aligns with the second-to-last opponent, the ball, or the halfway line, depending on proximity to the goal line. The assistant referee signals an offside offense by initially raising the flag vertically and subsequently, if the referee stops play, lowering it at an angle indicative of the offense location:

  • Flag pointed at a 45-degree angle downwards: offense in the third of the pitch nearest to the assistant referee.
  • Flag parallel to the ground: offense in the middle third of the pitch.
  • Flag pointed at a 45-degree angle upwards: offense in the third of the pitch furthest from the assistant referee.

Officiating offside can be challenging for assistant referees, requiring them to track player positions during attacks, consider offside positions at the ball’s play, and determine when offside-positioned players actively participate. The foreshortening effect, where distances between players distort visual perspectives, increases the risk of misjudgment, often underestimated by spectators. Some researchers argue that offside officiating errors are “optically inevitable,” suggesting the potential need for automated enforcement of the offside rule.

Exceptions to Offside

Since the inception of the first FA laws in 1863, a player has not faced penalties for being in an offside position at the moment a teammate takes a goal kick. The original “strict” offside law from 1863 would have deemed every player on the attacking side offside during a goal kick, as it had to be taken from the goal line. Under the initial laws of 1863, being offside from a throw-in was not possible. However, given that the ball had to be thrown in at right-angles to the touch-line, gaining a significant advantage from being ahead of the ball would have been uncommon. In 1877, the throw-in law was amended to permit the ball to be thrown in any direction, allowing a player to be offside from a throw-in.

Introduced in 1872, the corner kick initially had to be taken from the corner-flag itself, eliminating the possibility of an attacking player being in an offside position relative to the ball. However, in 1874, the corner-kick rule changed to allow it to be taken up to one yard from the corner-flag, opening the potential for a player to be offside. While offside offences have always been permitted from a free kick, they differ from other restarts of play such as the goal kick, corner kick, and throw-in. In 1920, a proposal by the FA to exempt free kicks from the offside rule was unexpectedly rejected by IFAB. Although the experiment enhanced the non-offending team’s position and increased goal-scoring opportunities, the proposal was withdrawn at the next annual meeting.


What constitutes an offside position in sports?

An offside position in sports occurs when a player is nearer to the opponent’s goal line than both the ball and the second-to-last defender at the moment the ball is played to them, unless they are in their own half of the field or level with the second-to-last defender or level with the last two defenders.

How is active involvement in play determined for an offside offense?

Active involvement in play for an offside offense is determined by factors such as gaining an advantage from being in the offside position, interfering with an opponent, or gaining possession of a rebound, deflection, or deliberate play from a teammate.

Are there variations of the offside rule in different sports?

Yes, variations of the offside rule exist in different sports. While soccer is the most well-known for its offside rule, other sports like field hockey and ice hockey also have variations of the offside rule tailored to the specific dynamics of each game.