The American Civil Liberties Union (search) of Pennsylvania asked a judge to throw out a state law aimed at fighting Internet child pornography, arguing it also blocks access to thousands of legitimate Web sites.

The group, along with the Washington-based Center for Democracy & Technology (search), filed a federal lawsuit in September, and the case went to trial this week.

In his opening statement Tuesday, John B. Morris Jr., a lawyer for the groups, told U.S. District Judge Jan E. DuBois that the law is "well-intentioned but technologically misguided."

Pennsylvania officials have forced Internet providers to block access to more than 800,000 legal Web sites, Morris said.

"This case is not about supporting anyone's ability to access child pornography," he said. "Our focus ... is access to (constitutionally) protected material."

But John Shellenberger, a senior deputy attorney general, said in his opening statement that the 2002 law does not infringe on First Amendment rights.

"We believe ISPs (internet service providers) have reasonably effective methods that do not significantly disable access to sites that do not show child pornography," he told the court. DuBois is hearing the case without a jury.

According to the lawsuit, the only way most Internet providers can block access to a particular Web site is to block its server computer, which may be shared by unrelated Web sites — preventing subscribers from viewing any of those sites.

Laura Blain testified Tuesday that a Web site she put up as director of her township recreation department could not be viewed by several people in June and July.

The page was caught up in a shutdown order, she said, and after days of phone calls her page was eventually transferred to another address.

"To me, this is more about free speech than it is about child pornography," she said.

According to a pretrial deposition filed by the plaintiffs, one shutdown order forced AOL (search) to block 400,000 sites from its users because of one offending Web page.

But Shellenberger said the state had no way of knowing how many Web sites have been affected by the law.

AOL spokesman Nicholas Graham said his company has received about 100 shutdown requests from Pennsylvania, complying with each one.

"AOL finds this kind of content abhorrent ... and we have a zero tolerance policy for it," Graham said. But he said the process blocks innocent sites, too, adding that AOL is interested in making the shutdowns "as efficient and exact as possible."