Child pornography isn’t illegal because the content is objectionable, but because having it be legal will increase the demand for it and directly contribute to an increase in child sexual exploitation. So it falls under the same free speech logic as directly inciting violence.
Child pornography is illegal because the law views it as equivalent to abusing a child or exploiting one, as well as for content. This is why loli and basically all forms of 'drawn' 'child pornography' are basically legal in the United States, some exceptions are states but they're not typically going to prosecute you for drawn shit (typically its added onto child porn charges or used for parole violations). They have better things to do. This comes under defense of the 1st Amendment. If this were the rationale, drawn child pornography would be illegal as well. Deep fakes are considered child porn because the court doesn't want to have to sift through what 'is or is not' child porn. Its a hard statute. This includes pasting minor's heads on porn actresses bodies, literally cutting them out from magazines and pasting them with glue. There's a reason for this, the court doesn't want to have to fuck around with what is or is not child porn. That's part of the reason it separated off from obscenity and why loli isn't included. They don't want to fuck around with the 1st Amendment at all, so its really cut and dry. Child porn is completely objectionable content as well as equivalent to
abusing a child in the eyes of the law. Its not merely inciting violence. If it were thought of as inciting violence or creating the demand for abuse, drawings could be included. The reason they aren't is because as I mentioned above, the statutes are designed to not even come close to touching the first amendment, and the case for drawings could be made and fuck up the statutes. Therefore, the law views it as actively participating in violence, hence why sentences for child porn are extremely harsh and unyielding. Hence why even viewing an image is a crime, not just possessing it or trading it. People have had child porn images transmitted through other innocuous files, and if you can prove you never viewed it as well as never intended to download it, you're fine. If you view it, you're
fucked, even if you deleted it and never intended to download it. Because simply viewing an image of child porn is illegal, intent or not.
This is also why child pornography was separated off of obscenity as well and had a specific set of laws and statutes created for it. Much, much harsher ones. If the government wanted to prosecute you for loli (some guy in Ohio or Iowa got Doujins seized and it fell under Obscenity), it'd come under obscenity and not child pornography. You'd also get far less time and I don't think obscenity requires you to register as a sex offender or not. Child Porn is automatic. Obscenity I think prosecutors can request as part of a plea deal or in terms of sentencing. Which can be denied.
Child pornography content was ALWAYS objectionable. This has never changed. In past years, it fell under obscenity (which is NOT protected speech. However, obscenity these days is such a clusterfuck it is very rarely used by prosecutors unless the targets are easy as fuck, completely dis-likable, poor, mentally handicapped or all four. Nobody wants obscenity to go up in front of the Supreme Court because Obscenity has been on its last legs for awhile now) whose direct definition is objectionable content. It got its own set of laws thanks to the internet and the erosion of obscenity laws that something else needed to be created for it.
Some shit still gets prosecuted under obscenity, which again, is not protected speech and speech the government directly finds objectionable in its content (no merits what-so-ever). Its rare and prosecutors aren't going to do it unless they're pretty sure you're completely fucked. But obscenity statutes still exist.
