Ashcroft v. ACLU
In Ashcroft v. ACLU, 542 U.S. 656 (2004), the U.S. Supreme Court invalidated the Child Online Protection Act, which would have required pornographers to take reasonable steps to restrict access by minors to porn on the internet.
This law, which the Supreme Court struck down, did not censor a single word or picture. It merely required the pornographers to screen their websites from minors, which can be done by credit card or other verification.
The Court shifted the burden to families to screen out the pornography rather than requiring the companies profiting from the pornography to keep its own pollution from children.