COPA makes it a crime to engage in any speech on the World Wide Web that is "harmful to minors" if that speech is "available to any minor." "Harmful to minors" is defined as "patently offensive" to minors, "prurient" to minors, and lacking certain "value" for minors. The statute applies to any speaker on the Web who has the "objective of earning a profit." The goal of COPA was to protect children from speech that Congress considered inappropriate for them. COPA does not apply to obscene speech or child pornography, both of which are and remain illegal on the Internet. It applies only to an ill-defined category of speech that adults are entitled to read, but that Congress thinks is inappropriate for people under 17.

Plaintiffs challenged the statute primarily on the grounds that it will restrict speech to adults, dumbing down the Web to the level thought acceptable for children, and that far more effective means exist to protect children.

Plaintiffs presented extensive evidence at trial that there was a huge volume of speech, protected for adults, that would be covered by the statute. This included works of art and literature, sexual education information, rap music, and even words in an online dictionary. Among the witnesses who testified to their concern that they would have to self-censor to avoid imprisonment were:

* Plaintiff Mitchell Tepper of the Sexual Health Network which provides sexual health information for people with disabilities,

* Plaintiff Adam Glickman of Condomania, an online information site and store for condoms

* Plaintiff Joan Walsh of Salon Magazine, one of the Internet's most successful online magazines

* Plaintiff Rufus Griscolm of Nerve Magazine, a highly respected online magazine with an emphasis on sex

The government largely argued that the statute only covered a small amount of speech, but when they were pressed, they were unwilling and even unable to define consistently the speech that they would prosecute. For example, the government asserted that a photo of topless women on Playboy's web site was not "harmful to minors" but a photo of topless women on Penthouse's web site was "harmful to minors" and a photo on another site of topless women whose breasts were obscured by stars was, the government claimed, "harmful to minors."

The government also argued that speech would not be eliminated, only resticted, because a web site can protect itself from liability under the statute by allowing access only to people who enter a valid credit card number. However, the evidence showed that many, if not most, people would refuse to enter a credit card number to obtain access to speech, that many adults didn't have credit cards (and many minors did), and that the credit card companies would not allow their cards to be used as a surrogate for verifying an Internet surfer's age.

When the Supreme Court remanded, it particularly directed the parties to consider blocking or filtering software. Under the First Amendment, a statute criminalizing speech, like COPA, is unconstitutional if there are less restrictive alternatives. The Court directed the parties to determine whether filtering software was an effective, less restrictive alternative.

Internet content blocking or filtering software is widely available. Congress has required every ISP to notify parents of its availability and it is now built into a great many ISP programs, including Vista , Microsoft's newest version of Windows. Internet content filtering allows parents to decide what sites their children can view, tailoring the filtering to the ages of each child in the home and to the values of the family. Filters usually can also track the Internet usage of any child, restrict Internet usage to times when parents are at home, or even notify parents if children are attempting to access prohibited sites.

Much of the trial focused on the effectiveness of content filters. The government spent over a million dollars in a complex study of their effectiveness. The district court ultimately found that filters were highly effective at blocking unwanted content. Most of the filters successfully blocked more than 95% of the unwanted content. They block speech that originates in the US as well as speech originating overseas. They block forms of Internet speech other than the Web such as video, audio, peer-to-peer, and email.

By contrast, COPA is itself wildly ineffective. It does not apply to overseas speech, which experts for both sides found constitute approximately 50% of the Web. It does not apply to video, audio, peer-to-peer, email, or any form of Internet speech other than the Web. It does not apply to non-commercial speech.

Other tools also exist by which parents can protect their children including education, placing the computer in a common room, and setting rules for Internet use.

For all of these reasons, the district court concluded after a month-long trial that COPA is unconstitutional and that there are less restrictive alternatives. The court of appeals affirmed and then also denied rehearing and rehearing en banc. The government has until mid-December to file its petition for a writ of certiorari.