Offside looks like the perfect use case for automation. Freeze the frame, draw the line, announce the decision immediately. Goal-line technology does this with goals. So why is football still using humans in a video room?

The remaining delays cluster around five things, and most of them trace back to IFAB Law 11. The key line in Law 11 is not the offside line itself but the principle that being in an offside position is not an offence. A player is penalised only if they are in an offside position when the ball is played or touched by a teammate and then become involved in active play — defined through concepts such as interfering with play, interfering with an opponent and gaining an advantage. That is the border between automation and refereeing, and it shows up in each of the five delays below.