My colleague Stephen Bainbridge points to an article about this subject by Betsy Malloy (draft available here). Prof. Bainbridge had earlier praised the Delaware Supreme Court's decision in Doe v. Cahill which held that "before a defamation plaintiff can obtain the identity of an anonymous [blogger from the blogger's ISP] through the compulsory discovery process he must support his defamation claim with facts sufficient to defeat a summary judgment motion" -- which is to say, "must submit sufficient evidence to establish a prima facie case for each essential element of the claim in question."
Thus, if you say that you're defamed by John Doe's comments, and Doe's comments seem to be opinion, or are uncontroversially true, or are otherwise not defamatory, your suit is thrown out before you get Doe's identity. (The court recognized that the subpoena can't be defeated by an argument that the defendant made false factual allegations but made them without "actual malice," or without negligence, as the case may be -- that can't be figured out until the defendant's identity is learned, but whether the statements are mere opinion often can be figured out without unmasking the anonymous blogger.)
Bainbridge has just pointed, though, to Prof. Malloy's short article criticizing Doe v. Cahill, suggesting that it's an important argument though he is not persuaded by it; and I wanted to briefly respond to Prof. Malloy's position.
As I see it, the problem with Prof. Malloy's piece is its assertion that the Doe v. Cahill standard would wrongly restrict claims based on actually false allegations (as opposed to claims that are mere opinion, which isn't actionable in the first place). Prof. Malloy seems to read the opinion as taking the view that statements in blogs are categorically opinion: "[T]he court argued that a reasonable person would not construe a blog as stating facts." "The court indicated that, because of the misspellings, hyperbole, and general nature of blogs, a reasonable person would likely conclude that they only represent opinions." "Though the court holds '[w]e do not hold as a matter of law that statements made on a blog or in a chat room can never be defamatory,' it seems to characterize blogs in such a way as to make it nearly impossible for plaintiffs to meet their burden."
Yet Doe did not go that far -- rather, it concluded that a reasonable person wouldn't construe "the blanket, unexplained statements at issue [in that case]" as stating facts. And the statements involved did sound much like the sort of thing that we'd normally interpret as opinion, especially when it comes from someone who doesn't give supporting evidence, who isn't a psychiatrist, and who is just engaged in anonymous chatter:
"If only Councilman Cahill was able to display the same leadership skills, energy and enthusiasm toward the revitalization and growth of the fine town of Smyrna as Mayor Schaeffer has demonstrated! While Mayor Schaeffer has made great strides toward improving the livelihood of Smyrna's citizens, Cahill has devoted all of his energy to being a divisive impediment to any kind of cooperative movement. Anyone who has spent any amount of time with Cahill would be keenly aware of such character flaws, not to mention an obvious mental deterioration. Cahill is a prime example of failed leadership --- his eventual ousting is exactly what Smyrna needs in order to move forward and establish a community that is able to thrive on its own economic stability and common pride in its town."
"Gahill [sic] is as paranoid as everyone in the town thinks he is. The mayor needs support from his citizens and protections from unfounded attacks..."
That indeed appears like the "subjective speculation" or "merely rhetorical hyperbole" that the court rightly said wouldn't constitute actionable defamation in the first place. Nothing in Doe v. Cahill strikes me as a statement that speech in blogs generally is somehow categorically opinion -- its finding of opinion had to do with the particular statements at issue in that particular case.
Likewise, Prof. Malloy argues that "the court's opinion ... fails to provide a plausible judicial outlet for plaintiffs." But this "fail[ure]" stems simply from the defamation law rule that you can't sue over mere insults -- you need to point to statements that a reasonable reader would perceive as factual assertion, not "subjective speculation" or "merely rhetorical hyperbole." If you can point to such statements (as would be the case in many of the hypotheticals Prof. Malloy points to), you are legally entitled to subpoena various records to try to discover the anonymous defendant's identity. But if all you can point to is speculation or hyperbole, then you aren't legally entitled to a judicial outlet (at least in the form of a libel lawsuit), whether or not the speaker is anonymous.
Now I have heard some argue that even nondefamatory insults -- which are constitutionally protected against civil liability -- should be subject to an "outing" remedy, through which a court allows subpoenas to be used in order to identify the speaker. I don't think is a sound view, but I can see the arguments for it. But it is a mistake, I think to criticize Doe v. Cahill on the grounds that it protects what would otherwise be actionable defamation on a blog.