Personal filters are intended to help parents control their kids' surfing (see a round-up at Internet Filter Report, or hang loose for an illuminating test later in this article).

Search-engine filtering prevents you from seeing certain search results. (Here's a test of Google's Safe Search).

Network-based software, aimed at libraries and other organizations, generally works through a local network; it may be part of a larger suite of software that controls employee computer usage. According to its maker, "Websense Enterprise delivers a comprehensive software solution that analyzes, manages and reports on employee Internet access, network activity, software application use and bandwidth utilization." (We see Big Brother smiling?)

Howzit work?
Long-time readers of The Why Files know our passion for explaining how things work, but disappointingly, the nuts-and-bolts of web filters remains an area of darkness. We do know that many filtering systems start by putting websites into categories - such as adult, gambling, or illegal MP3 downloads. The system administrator or computer owner then decides which categories are permissible.

Some filters also employ a keyword filter that is triggered by words or phrases like "breast," "p*rn," "se*" or "hot girls." Keyword-blocking has been criticized for blocking access to sites related to, say, "breast cancer" or "sexual health," but it's the kind of data-intensive activity that can easily be computerized, and is certainly cheap. To protect The Why Files from keyword blocking, we're using those funky asterisks in questionable words, like se*.

Often, an entire domain, like all of nasa.gov or whitehouse.gov is blocked if any page within it is adjudged objectionable.

In categorizing websites, filter makers generally claim to use a combination of digital and human scanning. They will not, however, reveal exactly what standards they use, or what sites they block. "There is no way to get the block list, you can't go to Google, for example, and ask them, say tell me everything," says Edelman. "Similarly, with the commercial services, they are not interested in telling you." Indeed, he argues that "the categorization scheme is absolutely a black box, you don't know the professional qualifications of the content classification staff, and those qualifications are dubious, given the mind-numbing work they have to do day in and day out."

The Why Files tried to ask Websense, a major vendor of software to libraries, about its procedures, but they did not return our phone calls. Some blocking vendors do allow you to check if a particular URL is blocked, but as critics point out, the blocking lists can change daily, so it can be difficult to know about, let alone comply with, the decisions of the many vendors in the business.

It's easy to understand why firms would want to conceal trade secrets, but the lack of information puts librarians and operators of web sites at a disadvantage. Will the software block legitimate searches related to health? Could The Why Files be blocked because we discuss, say, web filters that restrict p*rn?

In this approach to blocking web pages, user requests are directed to a server that acts as censor. Image: NOIE Australia.

Filtering the filth
While concerned parents worry that the Internet will give their kids access to a degrading world of depraved sexuality, many librarians worry about civil liberties. The fact that paid defenders of the first amendment run many libraries explains why some big-city districts, including Chicago and Los Angeles, may forego federal funds and forget filters.

Other library officials are waiting for details about costs. Barbara Dimick, director of the Madison (Wis.) Public Library, says her system is waiting to learn how much federal money will be affected by the ruling, but she's been unimpressed by filters to date. "We did a search two to three years ago, and the filters were remarkably awful, tended to screen out what you wanted to research, and not take care of all the sites that might be considered objectionable."

But while some large library systems may forego federal support in favor of setting their own Internet policies, others have taken a different tack. For one thing, for all that lip service about free speech, viewing po*nog*aphy is a real problem in some public libraries. "I have talked to a couple of students from big urban libraries who say it's very stressful," says Kristin Eschenfelder of the UW-Madison. "If a patron with a substance abuse problem or who is not totally mentally there comes in, using a workstation ...this person might be really scary, or threaten you when you tell him you can't use a computer." Some libraries that don't restrict por* on computers are facing sexual harassment lawsuits from their employees, who are disgusted by repeatedly clearing *orn from computer screens.

More important, filters may be better than critics say. Hampton (Skip) Auld, assistant director of Chesterfield County Public Library, near Richmond, Va., has publicly argued that the filters work. For two years, he says, his library has heeded a local decision to restrict Internet use, and, "There has been minimal over-and underblocking of sites." During those two years, in a system that serves 1.5 million visitors annually, he says, librarians have logged about 40 requests to unblock, and 39 to add blocks. "I have a high level of confidence that filters can be configured in a way that will minimize the over-underblocking problem," Auld says.

Critics, we must point out, counter that library users aren't always asking to have filters lifted. "I'm not sure the librarians are in any particular position to say," says Edelman. "They only know if a patron comes up and complains, and you have to be an awfully confident patron to know you have been overblocked ... and complain. We are all trained to defer to the computer, if it tells you you are asking for a po** site, and you can't have it, that's an embarrassing thing."

In the olden days, libraries bought books. Now they buy Internet access. Does filtering the Internet amount to censorship? Photo: Croydon Council

Controlling the filters
Still, Auld says a key to success is setting the filter accurately. Instead of filtering broadly, Chesterfield chose "minimal categories, only those that are meant to deal with obscenity, child pornography, or 'harmful to minors material.'" With only two of the five "adult categories" blocked, users should be able to reach sex education, swimsuit and lingerie sites. The block-by-word feature, long a bugaboo of filter opponents, is off.

Filters are working, Auld insists. When the county surveyed librarians, the number who said they had to clear po*rn from screens daily plummeted.

As a librarian who says filters can work, Auld admits he's become a pariah "in some circles," but says, "I've tried to speak from experience... I'm not saying everybody should use the filters. I don't think CIPA was a good law, mainly because these things should be worked out locally. I don't think filters are necessary in all situations. I'm saying that the filters work better than they have been made out to work."

It all depends on your settings. Can you set me straight?

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