Guest Blog by Augusta Wilson*

A Stanford environmental professor’s high-stakes defamation suit over a peer-reviewed critique evaluating renewable energy outcomes, came to an end last week. Dr. Mark Jacobson, professor of civil and environmental engineering and director of Stanford’s Atmosphere/Energy program, announced on February 22 that he will drop the defamation suit he brought in D.C. Superior Court against fellow environmental scientist Dr. Christopher Clack and the National Academy of Sciences.

The case revolved around a 2015 paper in the Proceedings of the National Academy of Sciences (PNAS) in which Dr. Jacobson and three co-authors argued that wind, water and solar resources could provide 100% of the energy needed in the continental United States by as early as 2050. In February of 2017, PNAS published a critique of the Jacobson paper written by Dr. Clack (currently the founder and CEO of Vibrant Clean Energy, LLC, and formerly a mathematician with the Cooperative Institute for Research in Environmental Sciences) and 20 co-authors. In that article, Clack et al. argued that the Jacobson paper “used invalid modeling tools, contained modeling errors, and made implausible and inadequately supported assumptions.”

On September 29, 2017 Dr. Jacobson sued Dr. Clack and the National Academy of Sciences in Superior Court in Washington, D.C., alleging (among other things) that the Clack article contained false and misleading information constituting defamation. Dr. Jacobson sought a retraction of the Clack article as well as $10 million in damages. In particular, Jacobson alleged that Clack et al. had wrongly accused him of making modeling errors when, he argued, he had simply made an assumption, a necessary part of conducting complex modeling. Jacobson also alleged that press coverage of the Clack article caused significant damage to his reputation. Both Dr. Clack and NAS moved to dismiss the case, pointing to a D.C. law intended to prevent so-called “strategic litigation against public participation” or “SLAPP” suits. The D.C. court held a hearing on the motions to dismiss the case on February 20, 2018. Following that hearing, Dr. Jacobson announced that he would voluntarily drop his suit.

Dr. Jacobson maintained that this was not simply a dispute between peer scientists, but rather a case of Dr. Clack knowingly and intentionally misrepresenting what had been done in the Jacobson paper. However, there are compelling reasons to believe that this was in fact a valid scientific debate on an important issue of public interest, and therefore a serious misapplication of defamation law. The Jacobson paper “promot[ed] a shift in the United States’ environmental priorities and policies toward almost exclusive reliance on wind, water and solar energy.”[1]
The Clack paper was a peer-reviewed evaluation of Jacobson’s work that “pointed out what [its authors] regarded as flaws in its methodology, assumptions and conclusions.” [2] As Dr. Clack’s motion to dismiss pointed out, if the criticisms lodged against Jacobson’s work were accepted as defamation, there would be a severe chilling effect on scientific debate on what is indeed an issue of significant public interest. Others analyzing this case have similarly argued that if scientists conducting research on a contentious issue (or scientific journals publishing such research) believe that their involvement in that particular subject comes with a significant risk of being sued for defamation, scientists will become more reluctant to conduct research in that area, journals will become more reluctant to publish about it, and important scientific discourse and developments that otherwise would have occurred may not.

Dr. Jacobson’s lawsuit is important as a potential example of a trend towards misuse of defamation law in the context of environmental and energy policy and the science that underlies it. A few years ago, the journal Frontiers in Psychology retracted a paper linking climate denial to conspiracist ideation, after the journal received threats of libel litigation. In another recent high-profile (if, admittedly, different) example, Bob Murray of coal giant Murray Energy brought a defamation suit against HBO late night host John Oliver when Oliver did an episode in which he took aim at Murray and the energy policies he has advocated. That suit was recently dismissed. Differences of opinion about climate science in particular, and appropriate policy responses, are frequently vehement. When directed against scientists by those who disagree with the policy implications of their research, this tactic has the potential to significantly impede scientific development.

Nonetheless, there is a line between those types of cases and cases in which defamation law is a legitimate tool that scientists can use of in order to defend themselves. The Jacobson v. Clack case naturally lends itself to comparisons with a well-known defamation suit brought by climate scientist Michael Mann, one of the researchers who developed the famous “hockey stick graph” showing an abrupt rise in global temperatures. Dr. Mann’s work became the subject of numerous fraud investigations after his were among roughly one thousand emails that were hacked and posted online in 2009 in the manufactured controversy termed “Climategate”. None of the investigations found that Dr. Mann had in fact committed any fraud. Nonetheless, in 2012 Rand Simberg wrote a blog post for the Competitive Enterprise Institute in which he suggested that Dr. Mann had used fraudulent methods in his research, and engaged in personal attacks and name-calling against him. Dr. Mann sued Simberg, the Competitive Enterprise Institute and others for defamation. [3] (The Sabin Center has previously written about the Mann case.)

The defendants in that case argued, just as Dr. Clack and his co-defendants did, that the suit should be dismissed under anti-SLAPP legislation. Both the trial court and the D.C. appeals court rejected that argument and allowed Dr. Mann’s defamation claims to go forward. The fact that Dr. Mann’s research had already undergone multiple investigations without any finding of misconduct, as well the particular harshness of some of the statements at issue, led the courts to hold that a fact-finder could reasonably conclude that defamation law should provide him with protection against and relief from further allegations of fraud.

The juxtaposition of the Jacobson case with the Mann case points to an inherent tension in the application of defamation law in the context of scientific research. On one hand, the Jacobson lawsuit can arguably be seen as a warning signal that defamation law may increasingly be used as a way to undermine scientists and chill scientific research and debate, particularly on hot-button topics like climate change. On the other hand, there may well be more cases to come like that of Dr. Mann, in which scientists find themselves the targets of large-scale and long-term attacks and need that same body of law to protect themselves.

There are some important differences between the Jacobson case and the Mann case that may serve as examples of the kinds of guideposts courts can use in this context. For example, the allegedly defamatory statements at issue in the Jacobson case were made by fellow scientists as part of a critique about the validity of certain methods and the reliability of Jacobson’s research results. In contrast, in the Mann case, the comments at issue involved calling a demonstrably exonerated scientist a “fraud” and comparing him to a child molester. Courts will likely increasingly be called upon to analyze these kinds of factors in order to differentiate between abuses of defamation law that may do serious damage to the freedom and integrity of scientific discourse, and legitimate uses of it that may help protect that discourse.


[1] Clack Memorandum in Support of Special Motion to Dismiss at 1, D.C. Superior Ct. 2017 CA 006685 B (Nov. 27, 2017).

[2] Id.

[3] Dr. Mann’s case is currently pending in the D.C. Court of Appeals. The Court of Appeals ruled that Dr. Mann’s case could proceed to trial. The Defendants petitioned the Court of Appeals for a rehearing en banc in early 2017. The Appellate Court has yet to issue a ruling on the motion for rehearing.

* Augusta Wilson is a Staff Attorney at the Climate Science Legal Defense Fund, which seeks to protect the scientific endeavor. CSLDF previously assisted with the representation of Dr. Mann in a separate dispute over open records requests, although it is not involved in Dr. Mann’s defamation litigation described above.




Add a comment

Comments are subject to moderation and do not necessarily reflect the opinions of
Columbia Law School or Columbia University.

LexisNexis Environmental Law and Climate Change Community 2011 Top 50 Blogs


This blog provides a forum for legal and policy analysis on a variety of climate-related issues. The opinions expressed here are solely those of the individual authors, and do not necessarily represent the views of the Center for Climate Change Law.

Climate Law Links


Academic Calendar  |  Resources for Employers  |  Campus Map & Directory  |  Columbia University  |  Jobs at Columbia  |  Contact Us

© Copyright 2009, Columbia Law School. For questions or comments, please contact the webmaster.