The Federal Judicial Center’s new Reference Manual on Scientific Evidence has stirred sharp criticism for its climate chapter, with Republican critics saying the guide crosses from neutral education into partisan advocacy. The debate centers on contributor selection, cited sources, and whether judges are being steered toward a particular view on climate litigation. Questions about outside influence and transparency have already prompted congressional scrutiny. The fallout touches judicial independence, the role of experts, and how courts should evaluate complex science.
The Reference Manual is widely used by judges who must weigh scientific issues they don’t encounter every day, so its tone and sourcing matter. The fourth edition arrived early this year and runs about 1,600 pages, aiming to brief courts on technical topics from forensics to climate attribution. Because judges rely on such guides, any perceived slant can shift how cases are framed before a courtroom even opens. That explains why conservatives reacted quickly and loudly.
Critics point to the climate chapter’s roster of contributors and its footnotes as evidence that the section leans heavily toward activist voices. Names called out include prominent climate academics and legal advocates with clear histories in climate litigation. That has Republicans worried the manual is not the neutral primer it advertises, but a vehicle to shape judicial thinking on suits against fossil-fuel companies and regulations. The involvement of those with prior advocacy roles raises sensible questions about impartiality.
Congressional Republicans flagged the matter and launched inquiries, arguing the influence runs deeper than casual consultation. “The Committee on the Judiciary is investigating allegations of improper attempts by the Environmental Law Institute (ELI) and its Climate Judiciary Project (CJP) to influence federal judges,” read a statement from House Judiciary Committee members Jim Jordan, R-Ohio, and Darrell Issa, R-Calif. That language captures the central charge: that programs and projects are trying to prime judges before cases land in their courtrooms.
The Climate Judiciary Project pushed back through a spokesperson who defended its work as rigorous and peer-reviewed. The statement said the curriculum is “fact-based and science-first, grounded in consensus reports and developed with a robust peer review process” and that suggestions otherwise are “without merit.” Supporters argue judges need accessible, accurate summaries of complex science, and they say trained experts are the right way to deliver that.
Jessica Wentz, one of the chief authors of the climate section, has a resume blending academia and advocacy that made critics uneasy. She is tied to a climate-focused project and has participated in high-profile climate litigation as an expert witness, including Juliana v. U.S. She also joined amicus efforts backing federal regulatory actions, which opponents say undercuts claims of neutrality when she helps draft guidance for judges.
Conservative legal voices warned the manual’s tone could have real consequences for litigation strategy and judicial outcomes. ‘It is alarming to see how far the Left has gone in its blatant effort to capture the judiciary. Its feeding of trial lawyers’ climate ‘science’ to sitting judges who will decide contentious litigation in this area short-circuits our system of justice,’ said Carrie Severino, a former law clerk for Supreme Court Justice Clarence Thomas and president of the Judicial Crisis Network. ‘When they can’t pass their extreme policies into law, they are attempting to use the courts as an end run around the legislative process,’ she added.
Other conservative attorneys see the issue as more than optics, calling out specific sections of the manual for relying on scholarship tied to plaintiffs’ lawyers. “The whole section of the guide is shockingly inappropriate—and if you look at the organizational meeting at the National Academies, intentionally so,” Michael Fragoso said. “But when you dig into it, it only gets worse. The section on attribution “science,” for example, was lifted in large part by a previous article written by the two authors and Michael Burger, who is himself a climate-plaintiff lawyer.”
Fragoso continued that attribution is the cornerstone of many lawsuits claiming fossil-fuel defendants caused particular harms, and he finds it troubling that the guide would present that material through contributors with advocacy ties. “Given that attribution is at the heart of these lawsuits, it’s shocking that the Judicial Center would let a plaintiff lawyer “explain” it to judges. It’s even worse that it’s hidden in a random footnote,” he said. Those concerns underscore why some Republicans want clearer lines between scholarly work and courtroom primers.
Michael Mann, a climate scientist cited in the manual, is a familiar figure in these debates and the source of past controversies. He authored the book the “New Climate War” and later resigned from a university role amid criticism over social media comments, and he has been both defended and attacked in public disputes. When asked about criticisms tied to the guide’s drafting, Wentz said “no comment.” Mann did not respond to a request for comment.
The clash over the Reference Manual’s climate section has already moved beyond op-eds and tweets into formal review and oversight. Republicans argue transparency, diverse sourcing, and strict separation from advocacy are essential if judges are to receive fair, balanced scientific primers. Expect more hearings, document requests, and public debate as lawmakers and interested parties press to know who shapes the materials that inform our courts.
