Hentai - Illegal in America?

So what's this about hentai being illegal in (North) America now? What constitutes an animated image being considered underage? Does it refer to teenagers as well as loli? And, if yes, what's the criteria for judging that? Help me out, world4ch, I need answers.

Hentai in general NEVER was illegal. Bible Black for example ALWAYS was legal because it didn't have little kids getting molested/raped. Only LOLI hentai was ever banned, and then the law was repealed anyway. So why is this thread still going?