ok ok. i've only started researching this problem 6 weeks ago, but i've read about 6-8 rulebooks all the way though(from the internet).
I can't actually speak for EVERY rulebook, just the 6-8 I've read.
I would - however - LOVE to read every rule book. I have only found 6-8 rulebooks on the internet however, NFHS not being one of them.
Here is one of the more interesting posts I've found - from NCAA men's.
http://www.ncaa.org/champadmin/baske...bulletin3.html
Reading between the lines on this memorandum lends me to believe that while offensive player backing in is illegal, and not called - defensive players using equal force to keep them physically from coming in is OK, as how can there be a foul on an action that was a response to a foul to begin with? But again, this is interpretation, never stated explicitly in an actual rulebook.
-David Jentz