Arcaeca said:
Kkkkkind of. Per Ashcroft, fictional/drawn child pornography are protected under 1A unless found to be obscene, but the prevailing standard for what counts as "obscene" set forth by the Supreme Court is, I kid you not, "I know it when I see it" and "patently offensive >:(". That is... there is no standard.
What happened was congress tried passing laws three times that made the whole fictional/drawn porn of apparently child characters illegal. The first two times the laws were challenged as soon as they went into effect and the Supreme Court swatted them down as unconstitutional. However, the third time that didn't happen and the law has been used with restraint by prosecutors (which is surprising as hell). It's mainly used to pile on charges for someone out on parole with a parole condition to not access any pornography. (Mainly convicted sex offenders.) Those cases would make for a lousy case challenging the law and likely fail. I honestly don't understand why the ACLU & others didn't challenge it immediately like the first two, so I assume it's that and/or congress managed to write it so it's difficult to challenge before it's been abused to deny someone their first amendment rights.
So technically loli & shota is illegal in the US, while realistically, no one's getting arrested and charged for having/producing it alone. This is part of why US-based companies are so strict about it. It really is illegal, so they have to act accordingly. The stuff with credit card companies banning all porn payments is only partly due to the law, it's mainly them caving to the anti-porn zealots whose goal is to get all porn banned worldwide.
That said, it doesn't excuse Pixiv's actions here. This seems much more caving in to the anti-porn zealots and/or US credit card companies than for any actual legal reason.