The US Supreme Court has upheld a law forcing public libraries to filter out internet pornography in what is being seen as a victory for attempts to protect children from obscene content.
Congress has struggled to find ways to shield children from harmful sites
It ruled that the 2000 Children's Internet Protection Act - which requires computers to be fitted with anti-pornography filters - does not violate rights to free speech under the First Amendment.
The 6-3 decision means libraries receiving federal technology subsidies must use software that screens out obscenity, child pornography and sexually explicit material deemed harmful to minors - or turn down the funding.
The unsuccessful appeal was brought by a coalition of libraries, library users and website operators who claimed the law turned librarians into censors rather than providers of information.
They said the software filters prevented library users from accessing information on subjects they had a legitimate right to know about - eg breast cancer, homosexuality, sexually transmitted diseases, gay rights and family planning.
Two other attempts by Congress to regulate child pornography on the internet had previously been blocked by the court.
Option to unblock
Reversing the judgement of a federal court panel in Philadelphia, Chief Justice William Rehnquist - who wrote the majority opinion - said the law did not turn librarians into censors.
He said the law was a "valid exercise of Congress' spending power", adding that it had "wide latitude to attach conditions to the receipt of federal assistance to further its policy objectives."
He added that, if a legitimate site was blocked, a user "need only ask a librarian to
unblock it or (at least in the case of adults) disable the filter."
The public library is the number one
access point for online information for those who do not have
Internet access at home or work. We believe they must have
equal access to the Information Superhighway.
American Library Association
Federal technology subsidies, which have totalled almost $1bn since 1999, are used to pay for internet access, automated catalogues and other services.
More than 14 million Americans use public library computers to do research and send and receive e-mail, especially low-income households with no other internet access.
The Supreme Court ruling drew swift criticism from the American Library Association, which said it would ask filtering companies to reveal what sites were blocked by their software and why.
Digital freedom campaigner the Electronic Frontier Foundation released a new study on Monday that suggested that popular filtering programmes blocked tens of thousands of web pages that had no offensive content.
A spokesman for the group said the law "holds library patrons and students hostage to faulty blocking software created with arbitrary standards foreign to their own communities."