In the US, until mid 2002, any kind of depiction of underage pornography was treated as real. Even drawing a pigtailed stick figure could theoretically land you 20 years in prison and a "sex offender" badge for life. The law was overturned in Ashc roft v. The Free Speech Coalition,
http://www.cnn.com/2002/LAW/04/16/sc...al.child.porn/ .
I don't know if there have been new laws passed in this area.