In a recent game a player was spinning the ball and not actually throwing from above and *behind* the head. Spinners only throw from above the head and perhaps slightly back and are therefore able to place their dominant hand more behind the ball. It is difficult to get so much spin on a ball thrown properly from behind the head.
How far back is “over and behind the head”?
Since a ball spinning that much is harder to control do referees consider it a wash?
USSF answer (August 10, 2009):
There is no rule that the ball may not “spin” when thrown. Complete requirements for the throw-in are spelled out in Law 15 (The Throw-In) in the Laws of the Game.
At the moment of delivering the ball, the thrower:
* faces the field of play
* has part of each foot either on the touch line or on the ground outside the touch line
* holds the ball with both hands
* delivers the ball from behind and over his head
* delivers the ball from the point where it left the field of play
All opponents must stand no less than 2 m (2 yds) from the point at which the throw-in is taken.
The ball is in play when it enters the field of play.
After delivering the ball, the thrower must not touch the ball again until it has touched another player.
And the referee is the sole judge as to whether or not this procedure has been followed.