What is the purpose of the requirement that both feet be on the ground when a throw in is taken? I can understand an advantage may be gained by the thrower jumping into the air while throwing but in this case both feet would be off the ground. I fail to see how any advantage is gained by lifting the back foot. As always your input is greatly appreciated.
USSF answer (October 15, 2008):
The Law requires that the person taking the throw-in be standing on both feet. This is what allows the flip throw-in to be legal, as both feet are on the ground.