Utah- Internet service providers say a Utah law requiring them to offer customers a way to block porn sites adds nothing new in the fight against pornography, quickly adding that a legal challenge to the law is likely.

Gov. Jon Huntsman signed the bill Monday that requires ISPs to notify customers “in a conspicuous manner” that they can get a filter or software that blocks known pornographic sites at no cost from the company. The bill takes effect immediately.

The filter must block “in an easy-to-enable and commercially reasonable manner, receipt of material harmful to minors.” The state’s consumer agency would test the effectiveness of the filters.

The bill, sponsored by Rep. John Dougall, R-Highland, is intended to help parents overwhelmed by advancing technology.

“Kids are much more savvy about what’s going on than their parents,” Dougall said during debate on the House floor. “We’re expecting (Internet) service providers to provide some option for protections. Government plays a critical role in that.”

But some ISPs say there’s little in the new law that isn’t already being done.

“The market has already responded to this issue,” said Pete Ashdown, president of Salt Lake-based XMission. “We have for many years provided an optional filter for our customers that they can turn on in Internet browsers.”

Ashdown said the new law, which charges the attorney general with the task of identifying and maintaining a database of porn sites, requires ISPs to begin incorporating whatever new Web sites the state adds to its watchlist.

“But I’m going to be awe-struck if they come up with anything that isn’t already on there,” he said.

The bill was watered down from an earlier version to appease ISPs, who argued it would arbitrarily block benign Web sites. That version would have censored offending Internet protocol addresses _ the series of numerical codes that point to Web servers which may host multiple Web sites.

The new version is still riddled with problems, ISPs say. For starters, it may be hard to separate Web sites launched by pornographers from others that may be deliberately created by mischievous competitors.

“I don’t know how the AG’s office is planning to arbitrate this matter, how they’re going to make those decisions,” Ashdown said.

The problem isn’t a new one. In 2003, Pennsylvania lawmakers faced a legal challenge to a similar state law that, in practice, blocked Web surfers from visiting innocent sites located in the same electronic neighborhoods as those peddling child porn.

That law, appealed by a prominent civil liberties group, was struck down as unconstitutional by a federal court in 2004. Now, the Washington D.C.-based Center for Democracy and Technology says the Utah law “will very likely lead to a costly litigation.”

In a detailed statement on its Web site, CDT lists numerous problems with the legislation, citing primarily its “blockage of innocent and unrelated” sites.

Officials at EarthLink, one of the nation’s largest Internet service providers, said Tuesday that a legal challenge to the Utah law cannot be ruled out.

“It’s a little early to tell,” said Dave Baker, spokesman for the company. “Of course, we wouldn’t necessarily be a part of a lawsuit, but First Amendment groups could challenge (the law).

“We’ve been down this road in Pennsylvania. And if that law can be struck down on constitutional grounds, this one will almost certainly face challenges.”

The legislation has angered First Amendment advocates in the state. ACLU of Utah Director Dani Eyer claims lawmakers are forcing government watchdogs to step in as “superparents” and censor Utah children’s access to the Internet.

But lawmakers say they’ve heard all the arguments against the bill and are confident the newest incarnation of the law will pass constitutional muster.

“The Pennsylvania law was struck down because it was not the least restrictive manner to address a compelling state interest,” Dougall said. “What we’ve done is use filtering technologies. It’s all very basic. Also, the consumer has the ability to opt in.”

Utah’s law, Dougall said, may be a model for other states.

“Do I believe this is a good piece of legislation? Yes. Do I believe other states can get on board? Yes,” Dougall said.

Under the law, companies that build and maintain pornographic sites would be required to label the content “harmful to minors.” And those who don’t comply could be charged with a Class A misdemeanor, punishable by one year in prison and a $2,500 fine.

The attorney general’s database would have to keep up as porn sites multiply or change Web addresses. Lawmakers have set aside $250,000 to cover the costs of the bill.

Officials with the Attorney General’s office did not return calls seeking comment Wednesday.