The Competitive Enterprise Institute received a letter on August 21, 2012 from an attorney representing Penn State University Professor Michael E. Mann that demands that CEI retract and apologize for a post on CEI’s blog,, written by CEI adjunct scholar Rand Simberg. The letter also threatens that they "intend to pursue all appropriate legal remedies on behalf of Dr. Mann."

"The Other Scandal in Unhappy Valley," the July 13, 2012 blog post at issue, criticized Professor Mann, a climate scientist who is recent years has become a leading advocate in the public debate for global warming alarmism. Mann was the lead author of research that created the controversial and much-disputed hockey stick temperature graph. The hockey stick was featured in the UN Intergovernmental Panel on Climate Change’s Third Assessment Report (2001), but was dropped in its Fourth Assessment Report (2007). E-mails from and to Professor Mann featured prominently in what became known as the Climategate scandal.

In October, 2012, Mann followed up with a defamation lawsuit against CEI and National Review. The initial complaint and subsequent legal filings appear below.

Legal documents