You might want to review the Dost test & some of the links I & others have posted in this thread. It's very possible that what you think of as child pornography may only be a subset of what the law holds to be illegal.

Pornographic images are more broadly defined than i had previously realized. Free speech is more restricted under case law than i had imagined, too; if it is "obscene" it can be banned. Not sure if i agree with that, but it is what it is.