In Brodie v. Independent Newspapers, the Maryland Court of Appeals recognized that the First Amendment requires certain procedural safeguards before the identity of anonymous bloggers and other Web site authors can be compelled. The Court joined the growing rank of courts in other states in applying a balancing test. The court refused to permit the disclosure of the identity of a number of individuals who anonymously posted comments on a Web site.
For a good overview of the decision, see Samantha Fredickson's article, A big win for anonymous Web speech, in the Spring issue of The News Media and the Law, published by The Reporters Committee for Freedom of the Press.
For additional details and commentary, and links to pertinent materials and other sites, see the discussion posted by Sam Bayard at the Citizen Media Law Project Web site.