NOTHING gets a journalist's attention like a subpoena. While authoritarian regimes silence critics by murdering or jailing them, journalists (and other critics) in the United States face gentler, but still effective, intimidation: libel lawsuits. Over the last few years, radical Islamists have tried silencing reporters, scholars and citizens by suing them for defamation, often successfully. But recent legal cases in California, Massachusetts and Minnesota suggest that the tactic may finally be backfiring, at least in the United States, if not in Britain, where libel laws overwhelmingly favor plaintiffs. The American lawsuits' outcomes represent victories for the free expression and public participation that the First Amendment guarantees.