In New York v. Ferber, 458 U.S. 747 (1982), the Supreme Court held that the government could restrict the distribution of child pornography to protect children from the child sexual abuse harm inherent in making it.
In Osborne v. Ohio, 495 U.S. 103 (1990), the Ferber proscription was extended by the Court to the mere possession of child pornography.
In Ashcroft case, the Court observed that this provision "captures a range of depictions, sometimes called 'virtual child pornography,' which include computer-generated images, as well as images produced by more traditional means."
The second prohibited "any sexually explicit image that was advertised, promoted, presented, described, or distributed in such a manner that conveys the impression it depicts a minor engaging in sexually explicit conduct."
The Supreme Court struck down CPPA in 2002 in Ashcroft v. Free Speech Coalition as a violation of the First Amendment for being too broad.