The District of Columbia Circuit Court of Appeals is right now receiving briefs on an interesting question: Does Washington’s 2010 law against so-called SLAPP suits (otherwise known as Strategic Lawsuits Against Public Participation) apply to libel and defamation claims in federal court or only to cases brought in Superior Court for the District of Columbia? Two U.S. district judges in Washington have denied defendants’ motions to assert the anti-SLAPP statute, which holds that in cases arising out of speech on matters of public interest, alleged victims must be able to show that they’re likely to succeed on the merits of their claim. The law, in effect, shifts the way courts decide motions to dismiss, doing away with the assumption that the plaintiffs’ allegations are true. It also restricts discovery, so plaintiffs usually have to show they’re likely to prevail without the benefit of depositions and documents from the other side.

Washington’s law is similar to those in more than two dozen other states, and the combined impact of the anti-SLAPP statutes, according to media lawyer Laura Handman of Davis Wright Tremaine, has been to reduce the burden of libel defense enormously. Amicus briefs at the District of Columbia Circuit by a group of media companies represented by Handman and by the American Civil Liberties Union and Public Citizen point out that e very other federal circuit that has considered whether state anti-SLAPP laws apply to cases removed to federal court under diversity jurisdiction has concluded that they do. Paul Alan Levy of Public Citizen, who defends bloggers accused of libel, told me that unless the District of Columbia Circuit rules that the same holds true for Washington’s anti-SLAPP law, libel plaintiffs will be able to forum-shop, adding out-of-town defendants to get to federal court and avoid anti-SLAPP defenses.

The anti-SLAPP issue at the District of Columbia Circuit was complicated this week when Washington lobbyist and lawyer Lanny Davis of Lanny J. Davis & Associates reached a settlement in his libel suit against 3M and 3M dropped its appeal of U.S. District Judge Robert Wilkins’s ruling that the anti-SLAPP rule doesn’t apply in federal court. But the appeals panel is also considering a case brought against the conservative writer Andrew Breitbart and his associate Larry O’Connor by former U.S. Department of Agriculture official Shirley Sherrod. Sherrod’s suit was filed before the Washington anti-SLAPP law took effect, so U.S. District Judge Richard Leondidn’t address the question of federal application as squarely as Wilkins when he denied motions to dismiss the case. Nevertheless, O’Connor’s lawyers at Baker & Hostetler and amici from the media, public interest groups and the District of Columbia Council have asked the appeals court to use the case as a vehicle to decide the question of the anti-SLAPP law’s applicability in federal court. (Breitbart died in March 2012.) The District of Columbia Circuit has just suspended the deadline for a response brief from Sherrod’s lawyers atKirkland & Ellis, presumably to give them time to address the recently filed amicus brief from Washington.

This is all backdrop to a fascinating libel case filed this week by Michael Mann, a Penn State climatologist who is widely credited with developing key evidence of global warming. Mann was part of a group of climatologists that won the Nobel Peace Prize in 2007 and has been labeled a leading visionary by Scientific American. But asMann’s complaint explains, opponents of his global warming theories were able to seize upon emails stolen from the Climate Research Unit at the University of East Anglia in the United Kingdom to raise questions about the integrity of Mann’s research. After the emails were published, Penn State, the University of East Anglia and five governmental bodies in the United States and the UK investigated Mann for manipulating data and engaging in scientific misconduct. None found that he had, but Mann has remained a target for those who believe global warming is a hoax.

Last July, when the Jerry Sandusky child molestation scandal tarred Penn State, Rand Simberg, a writer for the Competitive Enterprise Institute, posted an article at Openmarket.com that called Mann “the Jerry Sandusky of climate science.” Instead of molesting children, the article said, “he has molested and tortured data in the service of polluted science that could have dire economic consequences for the nation and the planet.” The post also called Mann “the posterboy of the corrupt and disgraced climate science echo chamber.” A few days later, Mark Steyn of the National Review followed up on Simberg’s post in an online column that liberally quoted from (and linked to) the CEI story. Steyn said he was “not sure I’d have extended that (Sandusky) metaphor all the way into the locker-room showers with quite the zeal Mr. Simberg does, but he has a point.”