Here are some tips concerning the only means for non-goalkeepers to legally handle the ball.
A throw-in is awarded when the entire ball passes beyond the vertical plane of the outside of either touch line (either on the ground or in the air). Should the ball fully break this plane in the air and curve back into play, the throw-in is still awarded. It is the assistant referee’s responsibility to indicate with the flag when the ball crosses this plane and to indicate which team should take the throw-in. If the AR is not sure to whom to award the throw-in, they are to raise their flag straight up and allow the center referee to make the call. Should the CR overrule the direction determined by the AR, the AR should immediately indicate the direction shown by the CR to demonstrate team unity. The throw-in will be taken from the point where the ball left the field of play (this position may need to be indicated by the referee team).
Both feet are to be on or behind the touch line through the entire throw. Watch for heels on the line which invariably are lifted while throwing. Back feet can drag across the ground so long as continuous contact occurs (toes can bounce during this maneuver). Both hands are to be used in a throw-in, though a curving ball does not necessarily indicate a foul throw (a throw-in not in accordance with the Laws). The throw cannot be done predominantly with one hand nor can it be dropped. Compliance with these requirements will be a judgment call by the referee team. The ball is to be thrown from behind the head and be released over the head, or just beyond the vertical plane of the forehead, in a continuous motion. A ball thrown-in that never enters the field of play (does not break the vertical plane of the outside edge of the touch line) is not a foul throw, did not re-start play, and therefore is re-taken by the same team.
Quite often, the Center Referee requests the AR’s to watch the thrower’s feet for compliance while the CR will watch the hands. It is the CR’s discretion to determine how she/he wants compliance to be observed. When AR’s are not available, the CR should not rely on assistance of this call from team linesmen. Moving slightly closer to the throw to watch for full compliance is advised.
Optimally, play should begin immediately upon the award of a throw-in. Common sense will dictate if the referee should delay play to relocate the attempted throw-in if the player isn’t where the ball left play (the throw should occur within a few feet of where the ball left play). The closer the occurrence is to the goal line, the more concerned the referee should be. At U10 level and above, a foul throw always results in a throw-in awarded to the opponent. Re-tries can be awarded in levels below U10. Verbal advisement is always appropriate at all levels.
The thrower cannot be the first player to touch the ball. If they are, an indirect free kick is awarded to the opponent at the point the infraction occurred. During a throw-in, the defense is not allowed to physically distract the thrower by jumping, waving arms, etc. The defense is also required to give two meters (six feet) clear to the thrower. The referee can consider such violations as cautionable offenses. The throw-in would be re-taken in such cases.
Should the throw-in go into the thrower’s goal without being touched by another player, a corner kick is awarded to the opponent. Should the throw-in go into the goal of the throwers’ opponent without being touched by another player, a goal kick is awarded to the opponent. Should the thrower’s goalkeeper handle the thrown-in ball within their penalty area (and be the first player to touch the ball), an indirect free kick is awarded to the opponent at the point where the ball was handled.
A player receiving a ball directly from a throw-in is not considered in offside position, though this protection expires once the ball touches any player.
This a trick question, since a foul can only occur while the ball is in play. If misconduct occurs (dissent, violent conduct, etc.) while the throw-in is setting up (the ball is out of play), the referee will announce the misconduct, administer the appropriate cards, and re-start play with the assigned throw-in.