WHEN I WAS a freshman in high school, one of my world-weary senior friends introduced me to the pleasures of our local university library. It was several stories high, packed with rack after unadorned steel rack of books. And, more glorious still, it had computers with a card catalog database named Melvyl on them.

Oh Melvyl, how long I have adored you!

In those first giddy months of my acquaintance with the university library, I used its computers to find books on a rather predictable topic for a teenager: sex. I considered the subject to be the absolute height of campy hilarity, but I also desperately and seriously wanted to know more about it. Oddly, the first book I sought out had to do with child porn: it was a collection of Lewis Carroll's erotic photographs of naked young girls.

Standing in the air-conditioned stacks at UC Irvine, I pulled the tiny volume from a shelf and beheld the colorized images of nude preadolescents with my own eyes. I'm not sure what drove me to seek out this book in particular, but I think I'd heard somewhere that the famous children's author and his work were not as innocent as one might think. Seeing Carroll's sexuality for myself was like a rite of passage – as far as I was concerned, I now had access to all of the censored parts of Alice in Wonderland. And that wasn't all. With the help of Melvyl, who continues to serve patrons of the UC libraries to this day, I could find books on any topic I desired. I spent the next three years visiting the university library whenever I could, researching everything from then-president Reagan's weapons programs to the history of homosexuality.

My access to knowledge made me fearless. Everything, no matter how disturbing or obscure, had its place in the Melvyl catalog. You could read about things and comprehend them, rather than shrink in horror from ill-conceived fantasies.

And that's why I'm so concerned about the Supreme Court's ruling last week. In a troublingly vague 6-3 decision that upholds the Children's Internet Protection Act, the court ruled that libraries receiving certain kinds of federal funding must install software on their computers that censors Web sites deemed "harmful to minors." Numerous studies have demonstrated that censorware is highly inaccurate – none of the available programs are able, for example, to distinguish between Dick Armey's Web site and a Big Fat Donkey Dick Web site. The software will therefore block users from viewing both.

In an era when budget cuts have forced libraries to scale back purchases of books and periodicals, censoring library patrons' access to the Web seems only about half a step away from censoring books outright. Catalogs such as Melvyl, which are now accessed via the Web, could conceivably be blocked by censorware set up to filter for certain words like sex or phrases that could be construed as hate speech (so you might not be able to view pages containing references to Randall Kennedy's excellent scholarly work Nigger: The Strange History of a Troublesome Word).

Kevin Bankston, an attorney with the Electronic Frontier Foundation, says it's unlikely that any librarian would condone blocking an online card catalog. But the problem, he says, is that "overzealous librarians" might set up their blocking software to censor Melvyl without realizing what they'd done. In cases like this, where a blocked site is clearly not harmful to minors, the CIPA ruling allows for the idea that librarians can unblock sites for adults and possibly for minors. "But they aren't required to do it," Bankston explains. "Moreover, there may be libraries that won't mention to patrons that they can request that the librarian unblock sites."

So, conceivably, a person in a local public library searching Melvyl via the Web for books about nineteenth-century pornography might have his or her search results censored. It's a great victory for conservatives: blocking access to "naughty" Web sites could also block access to "naughty" books.

"I think there will be multiple challenges to this law," Bankston says. "Maybe there will be problems with librarians not unblocking sites or hassling patrons about unblocking. Or maybe it simply won't be technically feasible to flip a switch and turn off the filtering software on one particular computer, especially if you have a large, distributed setup of terminals."

In the meantime, all the curious young people who want to learn about the world from books may find that Melvyl and other systems like it are no longer their faithful friends. Perverted by censorware, the library will no longer lead us boldly into free thought, but instead to fear and ignorance.