Touch judge
A touch judge is an official who monitors the touch-line in a game of rugby union or rugby league and raises a flag if the ball (or player carrying it) goes into touch. Touch judges also stand behind the posts to confirm that a goal has been scored following a penalty kick or conversion of a try. There are two touch judges, one for each touch-line and each holding a different coloured flag.
Rugby union
Rugby union touch judges support the referee by marking 'touch' (identifying when the ball leaves the playing area and comes into contact with something there or when the player carrying the ball steps out of the playing area), indicating successful kicks at goal and marking offside lines at set piece plays (the scrum and line out).
Depending on the relevant national regulations, touch judges can be recognised as 'assistant referees' and can have the authority to indicate foul play, support with pre-match protocols and other roles delegated to them by the referee.
In England, touch judges are only recognised as assistant referees when appointed by the RFU or by the relevant Referees' Society. Touch judges in the vast majority of community matches do not act as assistant referees and cannot comment on matters of foul play or other technical matters.
In test matches, it is normal for the referee and assistant referees to be connected by a radio link to aid the communication of all this information.
At elite levels of the 'sevens' variation of rugby union, additional in-goal assistant referees exist to support the referee with in-goal decisions.
Rugby league
In rugby league, touch judges can communicate with the referee verbally or through a number of specific flag and hand signals. These indicate specific breaches of the laws, for example forward pass, knock on and penalty offences, how play should restart and whether the ball was grounded correctly for a try. As in rugby union, touch judges stand behind the posts to confirm success of a penalty kick or the conversion of a try. Touch judge and referee signals and duties in rugby league are laid out in the laws of the game. In some matches, additional officials are used solely to determine whether a try has been correctly grounded. These are known as "in-goal" officials.