The precision problem

The offside law says a player is in an offside position when any part of their body that can legally score a goal is closer to the opponents' goal line than both the ball and the second-last defender.

That definition is binary. There is no clause for "by a meaningful margin." Either the attacker is ahead, or they are not.

What changed

The law itself has not really changed. What changed is the measurement tool.

• Naked eye: anything within a few centimetres looked level
• Television replay (pre-VAR): close calls remained close — too fast to draw lines
• VAR with manual lines: lines drawn by a person watching frozen frames
• Semi-automated offside technology: cameras and a sensor in the ball, automatic and faster

Each step in this progression made the law more enforceable as written.

The armpit and shoulder rule

The offside line is drawn at the lowest point of any body part that can legally score a goal. Hands and arms are excluded — they cannot score legally, so they do not put a player offside.

This is why armpits and shoulders matter. The shoulder is the boundary — it is the last part of the upper body that can legally score, so it counts in the offside measurement.

A goal disallowed because a shoulder was 1cm offside is a correct application of the law. The shoulder can legally score. It must be behind the line.

Semi-automated technology

Used at the 2022 World Cup and rolled out across major competitions, semi-automated offside (SAOT) works by:

1. Cameras tracking 29 body points on every player
2. A sensor inside the match ball detecting the moment of release
3. An algorithm calculating offside positions instantly
4. The result sent to VAR within seconds

The output is a 3D animation that VAR officials confirm before sending the recommendation to the referee.

The human margin has not vanished — VAR officials still confirm the call — but the line-drawing step is automatic. Decisions arrive faster, and the measurements are not subject to human error.

What the spirit of the law says

Offside was designed to prevent goal-hanging — attackers camping near the opposing goal waiting for a long ball. The original idea was that an attacker should not gain a positional advantage over the last defender.

That advantage was historically measured in metres, then in feet, then in the pre-VAR era in close-but-clearly-ahead. The technology has now reduced advantage to a number that can be smaller than the player's bootlace.

The question is whether 1cm of advantage genuinely violates the spirit of the rule.

Trial proposals

Several alternative formulations have been discussed:

• Daylight rule: only offside if there is visible daylight between attacker and defender
• Whole-body rule: the entire body must be ahead of the last defender
• Tolerance band: anything within a small measurement window counts as level

Trials have been run at various levels. None has been adopted into the universal Laws of the Game as of 2026/27.

Why this is a policy debate, not a referee error

When fans complain about a 1cm offside, they are expressing a policy preference: the law should require meaningful advantage.

VAR or SAOT confirming the 1cm decision is a procedural outcome: the law as written was correctly applied.

Both can be true at the same time. The decision was correct under the current law. The current law might still be the wrong standard. Changing it requires IFAB action — not VAR review.

Active versus inactive

A separate offside controversy involves whether an offside player is "interfering with play." A player can be in an offside position without committing the offence — they have to actually be involved in the move.

This is where human judgment still rules. SAOT can tell you a player is in an offside position. It cannot tell you whether they were challenging for the ball or distracting the goalkeeper. That part of Law 11 still requires the referee.