I read a lot about this issue recently on the Anime on DVD 
forum after Media Blasters released an anime called 
"Kite" extensively cut.

The upshot of the discussion was that the 
particular U.S. laws on the subject are extremely 
vaguely written, and could be interpreted to mean 
that anything drawn, written(!), or filmed with 
characters claiming to be, appearing to be, or even 
just dressing as minors could be considered child 
pornography.  

A recent court decision (the case of the ex-Disney 
executive) found that drawn material was not child 
pornography because it did not involve actual 
minors.  However, law enforcement being what it is, 
I do think it's safer to err on the side of 
paranoia as the U.S. releasers of H-anime do.  
(Having characters say they are "18" and going to 
"junior college".)  Half the women in any kind of 
anime are rather over-endowed for their supposed 
age, anyway.

--Atiya

(At least that "Sakura" is badly-drawn enough that 
she doesn't really resemble the character whose 
copyright she is presumably trying to infringe 
upon.)