Line Judge

A line judge is an official assigned to a specific boundary line whose job is to rule on whether the ball, or a player, is inside or outside that line, and in serving sports whether a foot crossed the line before it was allowed. The same role appears under many names: a line umpire in tennis, a line judge in volleyball and badminton, an assistant referee or linesman who runs the touchline in football, a touch judge in rugby, and a position literally called the line judge in gridiron football. Baseball and softball apply the idea to a fair-or-foul line, while track and field extends it to lane lines and the foul line of a jump or throw.

What unites these variants is a narrow, fixed spatial focus rather than overall control of the contest. A line judge concentrates on one reference line, makes an immediate in-or-out or fault decision, and communicates it with a standardized signal — a raised hand or flag, a point toward the court, or a spoken call — so the head referee or chair umpire and the competitors can react without delay. The line judge works beneath that head official, who coordinates several such judges and can overrule a call; many sports now reinforce human line judges with instant replay or automated line-calling technology. Wherever a boundary or a foot-placement line must be judged in real time, this officiating role recurs.