THE BURNING QUESTION libraries face today is whether to install filters on the computers they make available to the public for online research. Stumbling now and then onto lascivious material while searching online is practically inevitable and so should be a matter of concern. All sorts of tricks are used to steer innocent users toward pornographic sites. If, for example, you accidentally type "Infoseeck" for "Infoseek" or "Whitehouse.com" for "Whitehouse.gov," you'll get an eyeful of what might be described as presidential activity. As regular Internet users are vividly aware, nearly every online search yields at least one pornographic site.

Yet the American Library Association, which represents 57,000 librarians, has roundly declined to promote the use of filters to block access to pornographic sites. The ALA isn't even concerned that, by not using filters, libraries make truly enormous amounts of pornography available to young people. Leonard Kniffel, the editor of ALA's official publication for librarians, American Libraries, has written, "Kids don't have time to sit at a library computer and troll for smut, nor do they wish to." The constitutional, philosophical, and cultural arguments the ALA has marshalled against filtering are similarly tainted by a weird blend of naivete and ignorance. More important, the ALA's case against filters is just plain wrong.

Filtering, the ALA argues, directly contradicts the First Amendment, ergo, it's wrong, as is any form of censorship. This position warps the First Amendment into absolute protection for any and all expression. In its Intellectual Freedom Manual, the ALA defines intellectual freedom sweepingly as "the right of any person to believe whatever he wants on any subject, and to express his beliefs or ideas in whatever way he thinks appropriate."

Granted, the Supreme Court has been expansive in its opinions about what speech is, recognizing a range of activities from nude dancing to the wearing of arm bands as protected "speech." This, however, does not amount to First Amendment protection for any and all "speech": Court after court has held that some forms of speech deserve no protection at all.

Roth v. United States excluded obscenity from the protections accorded to free speech. The plaintiff had developed a lucrative mail order business selling erotic and obscene works, which were quaint in comparison to the online material filtering advocates want to block. Products Roth sold, works like Photo and Body and American Aphrodite Number Thirteen, were declared unprotected speech. Justice Brennan, writing for the majority, decided that not only was obscenity "utterly without redeeming social importance," but it falls into the same category as libel and is therefore unprotected.

Roth has been adjusted -- most notably by way of the "Roth Test" -- but its central argument is still intact. Miller v. California, another censorship case, added community standards to Roth's restrictions, placing the burden on communities and local judges. These and other cases have all made the point that the First Amendment is neither absolute nor ambiguous. Since our founding, obscenity and pornography have not been protected forms of speech, regardless of the Court and regardless of the medium used as "speech."

If the First Amendment allows that some forms of speech are not worthy of protection, why then does the ALA condemn filtering? The ALA argues that any restriction on the flow of information is repugnant. To stand for the dissemination of information, the ALA believes, it is necessary to stand against filters. Any limit, then, on the flow of any information is wrong.

This might be a more persuasive principle if librarians didn't violate it every day. I do not know of many libraries that maintain subscriptions to KKK materials, or routinely purchase "hate" books from, say, gaybashing groups. Librarians rightly object to these materials because the "information" contained therein serves no one but the hopelessly unredeemable. Furthermore, librarians often end up restricting information for the most lamentable reason: price. Hardly a librarian alive or dead has not rejected some very valuable resource simply because it cost too much. Budgetary constraints cause libraries to lose good, solid information all the time.

Let's not forget, too, that filtering can be refined to the point where almost no worthwhile information is accidentally filtered. Making such improvements to existing filters may not be easy and may require greater technical expertise. But it can be done. Indeed, it is being done and quite successfully. All the same, to argue, as the ALA does, that we must not filter anything for fear of blocking something worthwhile is akin to arguing that we must not prosecute any criminals for fear of convicting the innocent.

Furthermore, it is clear that the ALA has taken a stand against filtering because that appears to be the position of all intelligent people. Everyone knows, after all, that any form of censorship is odious. Yet, the majority of public opinion remains with filtering. Even some professional library organizations, such as the Association of College and Research Libraries and the National Commission on Libraries and Information Science have made statements that conflict with ALA's ne plus ultra anti-filtering views. It is not too much of a stretch to say that of the 50,000 ALA members, a sizable number are for using filters.

Librarians have always had to make distinctions between the worthwhile and the worthless. Filtering, you could say, is in their job description. And any librarian who cannot discern an important difference between sexmuseum.com and womenshistory.com clearly does not belong in a library.

We are fast approaching an epidemic of access to Internet pornography. Cases are now coming to light in which library access to the Internet aided and abetted child-molesters (such as the case of Jack Hornbeck, a convicted child molester who used a Los Angeles public library's Internet connection to distribute child pornography and to arrange sex with children). Moreover, a recent survey by Filtering Facts indicates that 45 percent of all Internet pornography obtained through libraries is being accessed by underage people. Since libraries now offer 50 percent of all Internet access outside the home, they are fast becoming America's chief purveyors of pornography.

If librarians do not make the case that hardcore pornography should be filtered, then others will make the logical deduction that librarians can't be trusted at all. And so, it is especially unfortunate that the ALA, which could have been a voice of reason in this debate, decided to pander to some imagined consensus against filtering. Rather than stand up for the professional prerogatives of its members, the ALA decided to undermine the standing of all librarians, suggesting that they are nothing more than delivery boys ready to pass along every kind of smut available online.

Mark Y. Herring has recently been named dean of library services at Winthrop University in South Carolina.