A member of the umpiring crew in football who is positioned on or near the sideline opposite the press box and behind the defensive secondary.
The side judge occupies the same side of the field as the head linesman. He is responsible for decisions regarding players on his portion of the field, including, but not limited to judgments on pass completions, interference, actions made by defensive backs, running backs and receivers. The side judge is usually responsible for keeping count of the number of defensive players on the field. He will also act as a second referee for field goal attempts.
The side judge is abbreviated as either "S" or "SJ."