tj,
You are in luck. Normally, the NFHS does not have much from their rules online, and one has to purchase the Rules Book from them for about $6. However currently there is a document on the history of the HS soccer rule changes posted on their website
http://www.NFHS.org which contains the following:
http://www.nfhs.org/scriptcontent/va...Content_ID=494
"2000
15-1-5: A throw-in must enter the field of play or the ball is awarded to the opponent."
So you can see that this has been the case since the year 2000. What exactly does the actual text of 15-1-5 say? That's not available on the website, so I'll have to type it out for you from my copy of the 2005-06 Rules Book.
"...If, on a throw-in, the ball fails to enter the field of play before it touches the ground, the ball is awarded to the opponent at the spot of the infraction."
Glad to be of help.
