It is not liable if its true

Floyd Abrams:

Pursuing a libel or slander suit has long been a dangerous enterprise. Oscar Wilde sued the father of his young lover Alfred Douglas for having referred to him as a "posing Somdomite" and wound up not only dropping his case but being tried, convicted and jailed for violating England's repressive laws banning homosexual conduct. Alger Hiss sued Whittaker Chambers for slander for accusing Hiss of being a member of the Communist Party with Chambers, and of illegally passing secret government documents to him for transmission to the Soviet Union. In the end, Hiss was jailed for perjury for having denied Chambers's claims before a grand jury.

More recently, British historian David Irving sued American scholar Deborah Lipstadt in England for having characterized him as a Holocaust denier and was ultimately so discredited in court that an English judge not only determined that he was indeed a Holocaust denier but an "antisemite" and "racist" as well.

On May 29 of this year, the potential vulnerability of a plaintiff that misuses the courts to sue for libel once again surfaced when the Islamic Society of Boston abandoned a libel action it had commenced against a number of Boston residents, a Boston newspaper and television station, and Steven Emerson, a recognized expert on terrorism and, in particular, extremist Islamic groups. In all, 17 defendants were named.

Those accused had publicly raised questions about a real estate transaction entered into between the Boston Redevelopment Authority and the Islamic Society, which transferred to the latter a plot of land in Boston, at a price well below market value, for the construction of a mosque and other facilities. The critics urged the Boston authorities to reconsider their decision to provide the land on such favorable terms (which included promised contributions to the community by the Islamic Society, such as holding lectures and offering other teaching about Islam) to an organization whose present or former leaders had close connections with or who had otherwise supported terrorist organizations.

On the face of it, the Islamic Society was a surprising entry into the legal arena. Its founder, Abdurahman Alamoudi, had been indicted in 2003 for his role in a terrorism financing scheme, pleaded guilty, and had been sentenced to a 23-year prison term. Another individual, Yusef Al-Qaradawi, who had been repeatedly identified by the Islamic Society as a member of its board of trustees, had been described by a U.S. Treasury official as a senior Muslim Brotherhood member and had endorsed the killing of Americans in Iraq and Jews everywhere. One director of the Islamic Society, Walid Fitaihi, had written that the Jews would be "scourged" because of their "oppression, murder and rape of the worshipers of Allah," and that they had "perpetrated the worst of evils and brought the worst corruption to the earth."

The Islamic Society nonetheless sued, claiming both libel and civil-rights violations. Motions to dismiss the case were denied, and the litigants began to compel third parties to turn over documents bearing on the case. In short order, one after another of the allegations made by the Islamic Society collapsed.

...

Read it all.

This group is not the only Islamic group that has attempted to suppress critical speech by lawsuits or threats of suits. CAIR has also settled suits it brought alleging defamation. Abrams suggest the US use the British system of requiring the loser to pay attorney's fees in these types of cases in order to inhibit frivolous suits that are meant to intimidate.