Public library officials say they're concerned about child pornography but don't want to stop people from doing legitimate research on taxpayer-funded computers.

Neither the Salt Lake County Library nor Salt Lake City Library uses Internet filters.

"All of us are wrestling with this problem," said Scott Russell, a spokesman for the county system. "The difficulty with filters is that most of them don't work."

Pornographers, Russell said, manipulate their addresses so "one day they're blocked and the next day they're not."

Dana Tumpowsky, community relations manager for the Salt Lake City Library system, said inappropriate Internet use "very seldom happens" in city libraries, but both library systems have designated computers intended for children that go to approved sites and do not allow complete Internet searching.

The situation at public universities is more problematic, because legitimate research requires more sophisticated searches.

Julie Hinz, assistant director for public services at the University of Utah Marriott Library, said the library is working with campus police and legal counsel to come up with a position that balances academic freedom and legal responsibility.

Of course, child pornography is illegal, and administrators have caught people in the past few months viewing child porn on U. computers, Hinz said.

Weber State University does not filter content for open lab computers but will soon require a network log-in that will make individuals accountable for the material they download and view.

There has been only one case of on-campus child pornography in which the viewer was caught, said Don Gardner, WSU chief information officer. More than a year ago, a relative of a professor was caught in the professor's office accessing child porn. The school called campus police, and the man was prosecuted.

"We're concerned," Gardner said. "We don't want to break the law."