• by Wendy Davis , Staff Writer @wendyndavis, April 1, 2010

Facebook has made a trove of data about its members available to anyone who knows how to use a search engine. But the social networking site doesn't seem to want people slicing and dicing that data for their own purposes.

Today it came to light that Facebook persuaded researcher Pete Warden to destroy a trove of information he collected about 210 million users by crawling the site.

Warden says on his blog he scrubbed the data after Facebook threatened him with litigation. While Warden doesn't elaborate, it seems likely that Facebook would have argued either that Warden infringed Facebook's copyright by making temporary copies of its pages, or that Warden subjected himself to liability by violating the site's terms of use, which prohibit people from scraping the site for information about users.

But both of those legal theories seem problematic. Any copyright infringement claim would be weak because data itself isn't copyrightable. And even if a Facebook page itself has some elements that can be copyrighted, it doesn't seem likely that a court would find Warden liable for infringement for making a temporary cache copy, cyberlawyer Venkat Balasubramani tells MediaPost. "I can't see the copyright argument as viable," he says.

Additionally, while some courts have ruled that sites can enforce their terms of use, any judge presiding over this matter would surely realize that Facebook is acting inconsistently in making the data available to search engines while banning researchers from crawling the site.

As Warden himself points out, Web crawlers have existed as long as the Internet. "Literally hundreds of commercial search engines have followed the same path and have the same data," he wrote.

Facebook's decision to publicize some information about users raises legitimate privacy issues. Just consider MIT's "gaydar" study, which involved figuring out who at the school was gay based on their Facebook friends.

And that's only the beginning. Surely researchers all around the country are mapping Facebook users' social graph at this moment -- with or without Facebook's consent. But it's Facebook, not the researchers, who made that data available to the public.