The Offside Trap
The offside trap is a defensive tactic where defenders step forward together to leave attackers in offside positions. Nothing in the Laws restricts it, but two things bound it: the position is fixed at the moment the ball is played or touched by a team-mate, and a defender who leaves the field of play is still counted, so stepping off does not take a defender out of the calculation.2, 3, 7, 9, 10
Key points
- ✓The trap is a tactic the Laws do not address: Law 11 penalises where an attacker was standing, not how the defence moved1, 7
- ✓The line is the second-last opponent, and the law says opponent rather than defender2, 3
- ✓The ball is the second half of the test: a player level with or behind the ball is not in an offside position however far past the defence they are2, 3
- ✓The goalkeeper is usually one of the two last opponents but not always, so a stranded keeper can leave two outfield players as the reference2, 3, 4
- ✓Level with the second-last opponent, or with the last two opponents, is not an offside position4, 5, 6
- ✓Timing must be precise, because stepping up after the ball is played does not make anyone offside7
- ✓A defender who leaves the field without permission is still counted, on the goal line or touchline, until the next stoppage or until their team plays the ball towards the halfway line and it is outside their penalty area9, 10
- ✓That counting runs against the defence: a defender cannot step off the pitch to take themselves out of the line, and one who leaves deliberately is cautioned when the ball is next out of play9, 10
Scenarios
The full rule
The offside trap involves defenders moving forward as a unit so that attackers are in offside positions at the moment the ball is played. The Laws say nothing about it as a tactic, and they do not need to: Law 11 penalises where an attacker was standing, not how the defence arranged itself. What the Laws do supply is the arithmetic, and three parts of it decide whether a trap has worked. The line is the second-last opponent, and the ball counts too: a player is in an offside position only if nearer to the opponents' goal line than both the ball and the second-last opponent, so an attacker level with or behind the ball is not in an offside position however far past the defence they are. The law is written in terms of opponents rather than defenders or goalkeepers, and that wording matters: the goalkeeper is usually one of the two last opponents, but if they have gone upfield for a corner or are stranded out of position, the two last opponents can both be outfield players and the line is drawn off the second-last of those. A player level with the second-last opponent, or level with the last two opponents, is not in an offside position. Timing is what makes the trap risky, because position is fixed at the moment the ball is played or touched by a team-mate, and defenders who step up after that have not caught anyone however synchronised the line looks a moment later. A defender who leaves the field of play without the referee's permission is considered to be on the goal line or touchline for the purposes of offside, which runs until the next stoppage or until the defending team has played the ball towards the halfway line and it is outside its penalty area. That provision runs against the defence rather than the attack: counting an opponent who is off the field can only move the second-last opponent nearer their own goal line, so a defender cannot step off the pitch to remove themselves from the line and push it upfield. A defender who left deliberately must be cautioned when the ball is next out of play.2, 3, 4, 5, 6, 7, 9, 10