From the Electronic Frontier Foundation
The Supreme Court has ruled repeatedly that the right to anonymous free speech is protected by the First Amendment. A frequently cited 1995 Supreme Court ruling in McIntyre v. Ohio Elections Commission reads:
Anonymity is a shield from the tyranny of the majority. . . . It thus exemplifies the purpose behind the Bill of Rights and of the First Amendment in particular: to protect unpopular individuals from retaliation . . . at the hand of an intolerant society.
The Electronic Frontier Foundation has been involved in the fight to protect the rights of anonymous speakers online. As one court observed in a case handled by EFF along with the ACLU of Washington, “[T]he free exchange of ideas on the Internet is driven in large part by the ability of Internet users to communicate anonymously.”