Passed in 1998, the law known as COPA creates a crime of knowingly placing on-line for commercial purposes any material that is "available to" and deemed harmful to minors.
Violation carries a fine of up to $50,000 and six months in prison, although there is a defence if the web site operator restricts access to minors by requiring use of a credit card or other means of age verification.
The case against COPA's validity began in 1999 when the American Civil Liberties Union (ACLU), on-line publishers and others argued that because the law bans material that is legal for viewing by adults it is inconsistent with the Constitutional right of free speech.
The case reached the 3rd US Circuit Court of Appeals, which struck down the Act, upholding an injunction to prevent it coming into force.
The US Justice Department appealed the ruling to the US Supreme Court which, in May 2002, upheld part of the law and referred it back to the lower court for reconsideration. While the ruling did not specifically cover the free speech issues, the Supreme Court said that COPA applies "contemporary community standards" to determine whether or not material is harmful to children.
Justice Clarence Thomas said that this approach "does not by itself" violate the Constitution; but he added that the court was not expressing views on whether the law may be unconstitutional for other reasons.
In March 2003 the Court of Appeals again struck down the Act, reasoning that COPA is unconstitutional because it is not narrowly tailored to target only pornography. Legitimate webmasters would be unfairly targeted, said the court.
And so the case has returned to the Supreme Court.
Arguing on behalf of the US Government, Solicitor Theodore B Olson stated that the volume of internet pornography meant that regulation was a necessity. Typing the phrase "free porn" into a search engine had given 6,230,000 hits, said Olson, according to the New York Times. "It's causing irreparable injury to our most important resource — our children," he argued.
The ACLU questioned whether other obscenity laws were being enforced rigorously enough. According to Ann Beeson, Associate Legal Director of the ACLU:
"Although the Government claims the censorship law is necessary to protect minors, it has not even used all of the tools currently available to protect them from sexually explicit content."
Despite long-standing federal obscenity laws, the ACLU noted in its brief, the Government has prosecuted only a handful of obscenity cases in the last 25 years, thus failing to protect minors from materials that are obscene even for adults. Other effective means that have been implemented include the mandated use of blocking software in schools and public libraries as well as the creation of a safe online environment for children using the ".kids" domain.
A ruling is expected before July.