Assistant referee (association football)
In association football, an assistant referee is one of several officials who assist the referee in controlling a match. Two officials, traditionally known as linesmen (or lineswomen if they are female), stand on the touchlines, while a fourth official assists administrative or other match related tasks as directed by the referee.
General duties 
All decisions by the assistant referee are only advisory to the referee; assistants do not actually make binding decisions. During the game one assistant referee oversees one touch-line and one end of the field utilising the diagonal system of control. The more senior of the two assistants will normally occupy the side of the field containing the technical areas, to help oversee substitutions. An assistant referee indicates matters to the referee (usually initially by raising his flag, but nowadays also by wireless communication devices, which can include "buzzer flags" and in the most senior games, additionally a microphone and headset link, which the referee may then act upon.)
Assistant referees were formerly called linesmen. In 1996, the name was changed, primarily to better reflect the modern role of these officials, and secondarily to become non-gender specific. They are also sometimes incorrectly referred to as "referee's assistants". However the term "linesman" is still commonly used.
Law 6 of the Laws of the Game outlines the general duties of the assistant referees, however their duties in a given game remain subject to the decision of the referee. These duties usually include indicating:
- When the whole ball has passed outside the field of play.
- Which side is entitled to return the ball into the field of play.
- When a player may be penalised for an offside offence.
- To assist the fourth official (if present) in notifying the center referee that a substitution is being requested.
- When offences or other infringements of the Laws of the Game have been committed of which the referee does not have an adequate view.
An assistant referee may also be called upon by the referee to provide an opinion regarding matters which the referee requires clarification on. Occasionally the assistant referee will assist in player management during free kicks, as well as provide visual assistance during penalty kicks. The assistant referees also usually assist the referee with preparatory and administrative functions.
Due to the nature of association football's offside rule, the assistants are generally better placed to assess whether a player is in an offside position than the referee. Assistants are generally expected to position themselves such that they are best able to make such judgements.
Fourth official 
The fourth official assists the referee in a variety of tasks, and may be called upon to replace another match official.
The fourth official is a recent addition to the officiating crew. English referee and administrator Ken Aston introduced the practice of having a named replacement referee in 1966, but the International Football Association Board (IFAB) did not officially create the position until 1991, and listed only areas of responsibility. The fourth official is simply instructed to assist the referee at all times, and his duties are largely at the discretion of the referee. His usual duties can be broadly divided into assisting functions and a replacement function (see below).
The fourth official typically has a table a short distance from the touchline between the two teams' technical areas, however his positioning is not defined by the Laws of the Game.
In usual practice, the fourth official assists the referee in the following ways:
- Assisting with administrative functions before, during and after the match;
- Assessment of players' equipment;
- Ensuring substitutions are conducted in an orderly manner;
- Notifying the referee of the details of the substitution, by means of numbered boards or electronic displays (where supplied);
- Notifying the teams and spectators, by means of numbered boards or electronic displays where supplied, of the amount of time added on at the end of each half, after having been advised of this by the referee;
- Acting as the contact point between the match officiating crew and any non-participants (such as stadium managers, security personnel, broadcast crews, and ball retrievers);
- Maintaining decorum in the teams' technical areas and interceding in situations where coaches, bench personnel, or substitutes become agitated;
In practice, the fourth official becomes a key member of the officiating team, who can watch the field and players and advise the Referee on situations that are going on out of his sight. The fourth official keeps an extra set of records, and helps make sure the Referee does not make a serious error such as cautioning the wrong player, or giving two cautions to the same player and forgetting to send off the player.
The fourth official played a significant role in the 2006 World Cup Final when fourth official Luis Medina Cantalejo informed referee Horacio Elizondo of the headbutt of France's Zinedine Zidane against Marco Materazzi, resulting in Elizondo showing Zidane a red card and sending him from the field. French manager Raymond Domenech accused Cantalejo of using the replay board to initiate the process that led to Zidane's ejection, which would have broken FIFA rules, but FIFA maintained that Cantalejo did not breach any rules and acted properly.
The fourth official serves as a replacement official in the event that one of the other officials (referee or assistant referees) cannot continue officiating (usually through injury).
In situations where an assistant referee is unable to continue, the fourth official replaces that assistant referee. In situations where the referee is unable to continue, the fourth official replaces the referee directly, or the senior assistant referee replaces the referee, with the fourth official in turn taking an assistant's position. Competition rules are supposed to clarify which of these options is to occur. If for some reason it is not stated, then typically the official with the most refereeing experience (either the fourth official or the senior assistant referee) will replace the referee.
Extra officials 
Assistants beyond those discussed above are generally uncommon. However, extra official roles have been trialled in a few international tournaments.
Fifth official 
For matches in the 2006 World Cup, FIFA assigned five officials. The role of the fifth official is to assist the fourth official in a variety of tasks, and potentially be called upon to replace another match official if necessary, for example in the case of injury.
If an assistant referee could not carry on his duties, the fifth official was to be the primary replacement, whereas the fourth official was the referee's primary replacement.
Additional assistant referee 
Recent trials, for example at the 2009–10 UEFA Europa League group stage, have been started to make place for an additional two assistant referees to be added to the game, positioned behind the goal lines, to "ensure that the Laws of the Game are upheld, informing the referee of incidents of any kind that he may otherwise have missed, particularly in key areas of the field like the penalty area and its surroundings," but only informing the referee of their observings through a wireless communication system. Their positioning gives a good view to assist the referee in "ghost goal"-type incidents. The trial was evaluated by IFAB technical experts.
Following a two-year experiment in the UEFA Champions League, Europa League and EURO 2012, as well as the AFC President's Cup and competitions in Brazil, France, Italy, Morocco and Qatar, the use of additional assistant referees was approved by the International Football Association Board (IFAB) in July 2012.
|Wikimedia Commons has media related to: Assistant referees|
|Wikimedia Commons has media related to: Fourth official|
- Refereeing & Disciplinary – The Fourth Official: the Scottish Football Association website. Retrieved on 28 February 2008.
- Zidane banned and fined for Materazzi headbutt – FIFA World Cup – ESPN Soccernet
- Definition of the fifth official: PDF file (page 8) quoting the "IFAB Agenda 2007". Retrieved on 14 May 2012.
- Use of a fifth official at the 2006 World Cup[dead link]: Oakland Tribune, 9 July 2006, via the FindArticles.com service. Retrieved on 28 February 2008.
- "Two extra pairs of eyes for referee teams". UEFA. 28 August 2009. Retrieved 29 August 2009.
- "UEFA Announce Two Extra Assistant Referees in Next Season's Champions League". Goal.com.
- "IFAB makes three unanimous historic decisions". FIFA.com. 5 July 2012.