Most federal judges have little scientific knowledge or training. They therefore often approach with some trepidation the many cases pending before them involving science, ranging from patent disputes to pharmaceutical class action suits to litigation over artificial intelligence.
To help acquaint federal judges with the basics of such subjects, the research and educational arm of the federal judiciary, the Federal Judicial Center (FJC), began publishing the Reference Manual on Scientific Evidence in 1994. It includes chapters on general topics such as the scientific method and others on more specific subjects that a judge may have to confront in a given case, such as epidemiology, toxicology, neuroscience, or computer science. Supreme Court Justice Elena Kagan, in her foreword to the most recent edition, writes, “The manual is the product of close collaboration among highly respected scientists, engineers, judges, and lawyers. It delves into the scientific subjects that judges most often face. It explains scientific approaches and explores scientific uncertainties and limits.”
No judge is required to consult the manual in any given case. It is simply a tool that is available if the judge thinks it will be useful. And because it is publicly available in print and online, the lawyers in a case can consult it as well.
In preparing new editions of the manual, the FJC has partnered since 2010 with the National Academies of Sciences, Engineering, and Medicine, a private institution established by Congress in 1863 to advise the government on scientific issues. That collaboration resulted in the widely praised Third Edition of the manual, published in 2011, and the FJC asked the National Academies to prepare a Fourth Edition, which was published at the end of 2025.
To fulfill this task, the National Academies utilized the same process that had worked so well in the preparation of the Third Edition. First, a thirteen-member committee was chosen to oversee the entire project, composed of nearly equal numbers of prominent scientists and experienced judges, all of whom had been identified and approved by the FJC and the National Academies. The co-chairs were the geneticist Fred H. Gage, known for his discovery of stem cells in the adult brain, and the senior federal judge Nancy D. Freudenthal. The other scientists were of equally high stature and accomplishment, and the other judges, a mix of liberals and conservatives, had all served with distinction for many years. Virtually all the members of the committee had prior involvement with educational projects concerning the interplay of science and the law.
The Fourth Edition committee, in collaboration with senior staff from the FJC and the National Academies who had worked on previous editions of the manual, selected authors for each of the twenty chapters. Some of these authors had participated in writing chapters for the Third Edition and others were new to the project, but all had established reputations for the rigor of their work and were carefully advised as to the purposes of the manual. They drafted the initial versions of their respective chapters, which were shared with the Fourth Edition committee for its review. Comments received from the committee members were shared with the authors, who undertook revisions to their chapters.
Once the Fourth Edition committee determined that the chapters had been sufficiently revised, they were submitted to panels of outside reviewers, some fifty in all, again including prominent scientists, judges, and others chosen for their diverse perspectives and technical expertise. Depending on whether a chapter was an update of a chapter that had appeared in the Third Edition, was significantly modified, or was entirely new, the panels consisted of two to five reviewers. Prior to the publication of the manual, the identities of the reviewers were kept secret from the authors of the chapters, so as not to interfere with their candid appraisals and suggestions.
Each reviewer was asked to answer at least five questions regarding the chapter assigned:
1. Is the content of the chapter clear and comprehensible?
2. Is the content accurate and of satisfactory quality for inclusion in the Manual?
3. Does the chapter identify the major topics and issues that would be of interest to judges?
4. Is the text written in a manner that is understandable to a non-technical audience?
5. What other suggestions for improvement, if any, do you have?
The reviewers were instructed not to answer these questions yes or no but to provide detailed written comments and suggestions, which typically occupied many pages. The reviewers of certain new chapters (including one on climate science) also had to answer questions more expressly directed to the subject matter of the chapter. The authors of each chapter were then required to respond in writing to each of the comments made by the reviewers and to submit a new version showing any changes.
A so-called monitor then carefully examined the reviewers’ comments, the authors’ responses, and the resulting changes in each chapter. In the rare instances where the reviewers and the authors substantively disagreed, the monitor had no power to decide who was right. But the monitor did have an obligation to make certain that all the reviewers’ comments and suggestions were carefully considered by the authors. Moreover, in the rare case where the authors did not agree to make a proposed change, the monitor had the power to determine whether their rationale was solid and adhered to the rigorous standards of the National Academies. For most of the chapters (including the climate science chapter), I was the monitor.
The final version of each chapter, along with the panels’ reviews and the authors’ responses, was then submitted to the Fourth Edition committee, as well as to the senior staff of the FJC and the National Academies, for their approval. The approval was unanimous.
The creation of the Fourth Edition of the manual was carried out with considerable care and thoroughness. It took several years to complete. When it was finally published at the end of 2025, both the FJC and the National Academies had every reason to be proud.
The Fourth Edition’s chapter on climate science was a long-overdue addition to the manual, as there had been substantial cases involving this complex scientific issue in the federal courts since at least the early 2000s. The chapter, written by two prominent experts from Columbia, was read by five independent reviewers, who were charged with answering, in addition to the five questions above, three additional questions:
6. Does the chapter accurately describe the certainty/uncertainty associated with the limitations of the climate models?
7. Does the chapter accurately describe the nature of current litigation involving climate science?
8. Do the authors provide appropriate caveats regarding any potential future litigation and the relevance of climate science to it?
While the reviewers’ answers to these and other questions and the authors’ written responses remain subject to the National Academies’ strict requirements of confidentiality, most of the comments and suggestions, though lengthy, were favorable, and those that raised concerns were accepted by the authors and resulted in helpful changes and clarifications in the language of the chapter, which was approved by the Fourth Edition committee.
The chapter is almost one hundred pages long and acknowledges from the outset the complexity of climate change and the difficulties of studying it. Thus any attempt to summarize its conclusions here runs the risk of oversimplification. Still, the essence is that our planet is getting progressively warmer and that, far from being an accident or solely attributable to natural variations, this is caused to a significant degree by human activity, such as emitting excessive quantities of carbon dioxide from various sources, including the combustion of oil, gas, coal, and other fossil fuels, thereby creating the so-called greenhouse effect, in which heat is trapped in the atmosphere rather than escaping into space.
Viewing climate change as scientifically controversial ignores what are now decades of studies confirming that it is occurring. Indeed, as early as 2007, a majority of the justices of the Supreme Court seem to have regarded it as scientifically likely. The Court’s decision that year in Massachusetts v. Environmental Protection Agency begins:
A well-documented rise in global temperatures has coincided with a significant increase in the concentration of carbon dioxide in the atmosphere. Respected scientists believe the two trends are related. For when carbon dioxide is released into the atmosphere, it acts like the ceiling of a greenhouse, trapping solar energy and retarding the escape of reflected heat. It is therefore a species—the most important species—of a “greenhouse gas.”
The purpose of the chapter on climate change is simply to confirm these mechanisms, explain how they work, and describe advances that have been made in measuring their impact.
This, however, did not deter climate change deniers from attacking the chapter almost immediately after it was published. One of the first attacks was a January 2026 article in National Review by Michael A. Fragoso, “Why Is Congress Funding the Judiciary’s Support for Climate Plaintiffs?” Fragoso is a partner at Torridon Law, a well-connected Washington firm that represents energy companies in high-stakes litigation. Arguing that the Fourth Edition’s chapter on climate science will be used to support plaintiffs in lawsuits brought against oil and other energy companies, Fragoso questions the objectivity of some of its sources. For example, he highlights that the chapter cites a finding from the Intergovernmental Panel on Climate Change (IPCC) to the effect that it is clear that human influence has helped cause global warming, but “nowhere,” he writes, “is it mentioned that IPCC is a United Nations apparat.”
The central thrust of Fragoso’s article, however, and the place where he touches a raw nerve, relates to the funding of the FJC:
The pending House appropriations bill for Financial Services and General Government funds the FJC to the tune of $35,121,000, while the Senate bill has it at $34,929,000. This is between $700,000 and $1 million more than their prior appropriation. Do House and Senate Republicans realize that they are funding ex parte propaganda for climate-change plaintiffs? Do the appropriators?
Congressional funding for the FJC is not mixed into the general funding for the judiciary but is a separate line item. This vulnerability was not lost on several members of the House of Representatives. Seemingly in response not only to Fragoso’s article but also to a letter criticizing the chapter by the attorneys general of numerous states that depend for revenue and employment on large oil, gas, and/or coal companies, these House members complained that the climate science chapter “appear[s] to have the underlying goal of predisposing federal judges in favor of plaintiffs alleging injuries from the manufacturing, marketing, use, or sale of fossil-fuel products.”
In response, the FJC, facing a threat of reduced funding, announced in early February that it would delete the climate change chapter from the Fourth Edition of the manual, which it had not yet distributed. The FJC did not suggest that the science in the chapter was substantively wrong but rather that the “ongoing criticism of, and controversy around, the climate science chapter would detract from the Center’s ability to carry on the broad range of its valuable research and education.” This prompted a letter to the FJC in late February from various senators and representatives, all from states less dependent on fossil fuel companies, in which they stated their “strong objection to your decision to rescind critical non-partisan guidance on climate science” from the Fourth Edition and asked that the chapter be reinstated—to no avail.
This was not the end of the story. The National Academies had already made publicly available on its website the entire Fourth Edition, including the climate science chapter, and initially declined to delete it despite considerable pressure to do so from the same politicians who had put pressure on the FJC. As the then president of the National Academies, Marcia McNutt, wrote in a letter to The Wall Street Journal, the climate science chapter “was developed under rigorous procedures of the National Academies” and “is consistent with the current scientific understanding reflected in the broader peer-reviewed scientific literature.”
Although technically a nongovernmental body, the National Academies get a great deal of their revenue from government grants; for example, the largest part of the funding for preparing the Fourth Edition came from the National Science Foundation, a federal agency. And then President Trump joined the fray, writing on Truth Social that the National Academies were run by “Radical Left Dumocrats” and that taxpayers should not be funding “Climate Fraud.” On August 9 the National Academies announced that they had “determined that questions about the processes used to develop the chapter warrant an independent review, and the chapter will not appear on our website while that review is underway,” and that the review
is about the process used to produce the chapter and not about the validity of climate science. The focus is on our own procedures and whether they were adequate to ensure the highest standard of objectivity that this institution requires and our nation deserves.
The result is that neither judges nor the public has access to a detailed chapter on climate science that was developed over two years in accordance with multiple checks and balances and whose scientific validity is not at issue, at least as far as the National Academies are concerned.
Some of this is eerily reminiscent of the substantial efforts made a few decades ago by tobacco companies and their congressional supporters to minimize or deny outright the scientific evidence that cigarette smoking causes lung cancer (and is addictive as well). But it also partakes of the efforts of the past year or so not only to deny other scientifically validated conclusions but also to use the power of the purse to enforce such denialism, even when it involves a supposedly independent branch of the government—the judiciary.
In 1633 the Roman Inquisition convicted Galileo Galilei on suspicion of heresy for daring to assert that the earth was not the center of the universe but revolved around the sun. He was required to abjure his opinion but afterward was rumored to have quietly muttered, “And yet it moves.” We may try to deny that human activity is a major cause of the rapid warming of our planet, which has already begun to show signs of looming catastrophe. And yet it warms.