It's a nightmare every librarian dreads: Someone sees a child viewing pornographic material on the library's PC, which is connected to the Internet. Or worse, someone in the library catches an adult showing pornography to a child. A quick call to the media and City Hall, and soon a torrent of controversy erupts as outraged citizens, politicians and the media tell the library to reign in the smut or else.

In 1997, that nightmare became reality for the Austin, Texas, Public Library. To gain control of the situation in the face of intense media scrutiny, the library quickly installed filtering software on the two Internet-enabled PCs at each of the city's 19 library branches.

Not every public library in the country faces such a scenario, but an increasing number of libraries are turning to filtering software to limit access to the vast amounts of indecent material available on the Internet. Last year, however, a federal judge ruled against the use of filtering software in a Virginia library.

Dark Side of the Net

There's no question that the Internet has become, in a few short years, a radical and even revolutionary form of information access. The proof of its popularity can be found in the statistics showing that tens of millions of Americans are now surfing the Internet and millions more log on each year. The same heavy demand for access can be found in our libraries. Sixty percent of the country's public libraries offer Internet access directly to the public, according to the American Library Association (ALA). That's up from 28 percent in 1996.

But what makes the Internet so wildly popular -- free and unfettered access to all sorts of information from around the world -- also has its dark side -- easy-to-reach Web sites loaded with extremely pornographic material. As libraries embrace the Internet as yet another source of information, they must confront the dilemma of whether to provide full access or to limit what patrons can view.

The ALA, the American Civil Liberties Union and other free-speech advocates have strongly resisted having libraries play the role of Internet censor. But parents and patrons who use the libraries on a regular basis have pressured libraries in a growing number of communities to devise some kind of barrier to viewing sexually explicit material from the Internet on library PCs.

Faulty Filters

The response by many of these libraries has been to install filtering software, which is used to block access to unwanted materials on the Internet. Filters look for characters, codes or strings of words deemed indecent. So far, about 15 percent of libraries with Internet access have installed filters, according to the ALA. Some of the leading products include SurfWatch, from Spyglass Inc., Cybersitter, from Solid Oak Software, Cyber Sentinel, from Security Software Systems and Cyber Patrol from The Learning Company.

Originally, civil libertarians supported filters as a more acceptable alternative to laws that tried to ban indecent material outright. Lawyers who challenged the original Communications Decency Act of 1997 pointed to filters as proof that users, not government censors, were the best defense against offensive material on the Internet.

Now, however, civil libertarians have widely criticized filters as ineffective because they fail to screen out all harmful material while blocking inoffensive material. Filters can block strings of words without regard to context. For example, they can block such topics as Essex County and chicken breasts, and such innocuous Web sites as Redbook magazine and Godiva Chocolatier.

Just as importantly, they cannot distinguish pornography from art or literature. Because of these software limitations, computer users lose access to useful, valuable information along with the pornography. While a home computer user may be willing to sacrifice access to Web sites to avoid pornography, when a tax-supported library board makes that decision for its