Law 6 - The Assistant Referees
Source - FIFA.com
Duties
Two assistant referees may be appointed whose duties, subject to the decision of the referee, are to indicate:
- when the whole of the ball leaves the field of play
- which team is entitled to a corner kick, goal kick or throw-in
- when a player may be penalised for being in an offside position
- when a substitution is requested
- when misconduct or any other incident occurs out of the view of the referee
- when offences have been committed whenever the assistant referees have a better view than the referee (this includes, in certain circumstances, offences committed in the penalty area)
- whether, at penalty kicks, the goalkeeper moves off the goal line before the ball is kicked and if the ball crosses the line
Assistance
The assistant referees also assist the referee in controlling the match in accordance with the Laws of the Game. In particular, they may enter the field of play to help control the 9.15 m (10 yds) distance.
In the event of undue interference or improper conduct, the referee will relieve an assistant referee of his duties and make a report to the appropriate authorities.