Are SLAPP suits illegal?
No, parties can attempt to file such suits, but the First Amendment’s
petition clause guarantees the right of all interested parties to attempt to
enlist the government on their side of an issue or dispute. The vast majority of
the case law and commentary — both popular and scholarly — supports that right,
and suggests that the remedy for dissatisfaction with the statements of another
party is more speech directed toward government, not more litigation.
Do anti-SLAPP laws apply to online libel suits?
In 2001, U.S. District Judge David O. Carter determined that California’s anti-SLAPP statute does apply to cyber-SLAPPs. (See Global Telemedia International Inc. v. Doe et al., 132 F. Supp. 2d 1261 (C.D. Cal. 2001))
In 2003, the Massachusetts Appeals Court cited that state’s anti-SLAPP statute in throwing out a libel lawsuit against a Web site operator whose posted statements suggested a town official was a Nazi. (See MacDonald v. Paton, 57 Mass.App.Ct. 290 (2003) and "State appeals court rules online libel suit was really SLAPP.")
Other state anti-SLAPP statutes may also apply to online libel suits. See "Anti-SLAPP statutes: state summary" for a state-by-state list.