University of Pennsylvania climate scientist Michael Mann’s losses in court continued to mount Thursday when a D.C. Superior Court judge denied his request to reconsider sanctions against him for having “acted in bad faith.” 

As a result, he owes more than $28,000 to two bloggers, who once faced $1 million in damages that a jury had awarded to Mann in his defamation suit against them. The ruling also had strong words concerning Mann’s conduct in the case, accusing him of presenting figures to the jury that he knew to be incorrect. 

“I think this goes more towards showing that climate skeptics have been right about Mann all along. I mean, we've always questioned his honesty,” Steve Milloy, senior legal fellow with the Energy and Environmental Legal Institute and publisher of JunkScience.com, told Just the News.

Sending a message

In February 2024, a D.C. jury awarded Mann $1 million in a defamation suit against Rand Simberg and Mark Steyn, who had criticized Mann’s controversial hockey stick graph, purporting to show a drastic rise in temperatures in the last century. Many scientists have questioned Mann’s conclusions and methods in coming up with the influential graph. 

In his suit against the bloggers, Mann contended that as a result of their posts, his reputation was harmed, which resulted in the loss of grant funding in the years following the bloggers’ statements. After the jury awarded Mann $1 million, he boasted of his victory, telling NPR, "I hope this verdict sends a message that falsely attacking climate scientists is not protected speech."

Many were concerned about the impact of the ruling on the ability of researchers to scrutinize the findings of climate scientists who come to alarming conclusions about global warming’s impacts, as well as the ability to criticize Mann’s behavior. Mann is known for his vitriol against those who come to different conclusions about climate change. 

Mann's win turns into loss on finding of "false representations" to the court

However, fortunes turned on Mann in the two years that followed the jury’s decision. In January, Mann was ordered to pay National Review $530,820, under "anti-SLAPP" laws that protect people from retaliatory legal action in matters of public concern. The court ruled that, as a publisher, the publication was not liable for the bloggers' posts. 

Last month, Mann dropped his appeals in exchange for the publication dropping its request for legal fees, The Philadelphia Inquirer reported. 

In March 2025, D.C. Superior Court Judge Alfred Irving lowered the award to $5,000, calling the jury’s $1 million award “grossly excessive.” 

Last May, Irving sanctioned Mann’s lawyers, in part, for having acted in “bad faith” in his libel suit. According to the ruling, Mann’s attorneys “presented erroneous evidence and made false representations to the jury and the Court regarding damages stemming from loss of grant funding.” 

In his ruling Thursday, Irving held Mann responsible for the false representations to the jury. Irving explained that Mann had elected through his attorneys to present to the jury claims that he had lost $9.7 million in grants as a result of the bloggers’ posts. However, during a third round of the discovery process preceding the trial, the amount was corrected to $112,000.

Mann and his attorneys had argued there was no harm in presenting the $9.7 million figure to the jury because the defendants knew it was corrected during discovery and expected they would bring that fact out during cross-examination. However, Irving explained in his ruling, the jury was never made aware of the correction, and Mann and his attorneys never provided a plausible explanation why they presented the jury with figures they knew to be incorrect.

Irving called the actions “particularly troubling,” because the figures presented to the jury were central to Mann’s defamation cases, and Mann was represented by “very skilled and seasoned attorneys.” 

“The court rightfully concluded that plaintiff and his attorneys acted in bad faith and that their litigation tactics cannot and should not be condoned in this jurisdiction,” Irving said in his ruling. 

"The court’s duty to punish and deter bad faith litigation tactics," judge says

Irving also held Mann responsible for the conduct, saying he was obligated to ensure the facts of his case were presented truthfully. This would allow the jury to reach a fair and reasonable decision based on the facts of the case. 

During Mann’s own testimony, Irving noted, he often expanded his answers and exceeded the bounds of the questions being asked, but he only did this “when it suited him.” He never took these opportunities to correct the incorrect figures being presented to the jury.

Irving stated that the only explanation the court could arrive at to explain the behavior was that Mann and his attorneys knew that if the $9.7 million figure went unchallenged, the jury would have something tangible on which to base their damages.

“While Plaintiff and his attorneys find nothing wrong with such practice, the court simply cannot condone such bad faith litigation tactics, particularly in a case that had been zealously litigated across several years and a case involving complicated facts. Thus, the court’s ruling must stand. It is the court’s duty to punish and deter bad faith litigation tactics,” Irving ruled. 

Nearly $3,000 in sanctions

Mann was ordered to pay Simberg $16,762.82. The defendant had sought reimbursement for fees he incurred in responding to Mann’s motion for reconsideration, but Irving denied that request. Mann was also ordered to pay Steyn $11,404.80. These awards include $2,838 as a sanction for Mann’s “bad-faith trial misconduct.” 

Milloy agreed with Irving that Mann was responsible for the false evidence presented at the trial, but he said Irving shares some of the blame, too. Going into the trial, Irving had expressed doubt, Milloy said, that the evidence supported Mann’s case. 

“So why do we have the trial? Why did this go on for 12 years? Why do this to the defendants? So ultimately, the bad seed is Mann, but the justice system is also a problem,” Milloy said. 

Just the News reached out to Mann for a response to the court’s decision and to ask if he plans to appeal, but didn’t receive a response. 

Kevin Killough is the energy reporter for Just The News. You can follow him on X for more coverage.