Question Number: 28091

Law 6 - Assistant Referee 1/3/2014

RE: Adult

J varney of Derby, England asks...

This question is a follow up to question 21165

Why do linesmen have to be on a particular side?

Answer provided by Referee Joe McHugh

Hi
In what is called the Diagonal System of control, the referee controls play by patrolling a line roughly diagonally across the length of the field from corner flag to the opposite corner flag. The two ARs are positioned on the touchlines on the opposite diagonal, patrolling that half of the touchline farthest from the referee.
If the referee decides, as is done most often, that he wants the assistants to be on the side of left backs that is the side that they patrol. That is the Diagonal System that referees use most and that they are more comfortable with. You might notice on some repeats of older games that assistant referees can be on the opposite side that is right backs. The FA at one time encouraged rotation of sides by ARs but that rarely happens now.
The referee in his running pattern will always try to keep the assistant in his view generally with play between himself and the AR. When play switches to the other half the referee moves across the diagonal to again having the AR in his view with play kept between them. Offside will be viewed by the AR in that half of the field looking across from the left back / right wing side.
The advantages are:
1. It gives two distinct viewing angles on play.
2. The referee most times does not have move into playing traffic and can rely on the ARs for calls close to them.
3. It allows referees to get a better 'angle of view' as many times that movement can be away from the ball.
4. It tries as best it can to eliminate 'blind spots' on the field of play with total coverage of the field of play.

Answer provided by Referee Gary Voshol

Assistant referees should be diagonally across the field from each other for the best coverage of the field. One AR is responsible for offside at each end.

That said, which diagonal is used (NE/SW or NW/SE, aka left or right backs) is often recommended and sometimes mandated by the competition or referee association rules. I think that can be a mistake. Sometimes there are times when AR's should use a non-traditional diagonal - field conditions, sun, crowd, etc. And unless refs and AR's practice the 'reverse' diagonal sometimes, they won't know how to do it when it's necessary.