Attorney General Bonta Sends Letter to Federal Judicial Center Strongly Opposing Removal of Climate Science from Judicial Manual

OAKLAND — California Attorney General Rob Bonta joined a coalition of 23 attorneys general, the Cities of New York and Chicago, and Harris County, Texas in a letter to the Federal Judicial Center (FJC) strongly opposing its decision to strike the chapter titled, “Reference Guide on Climate Science,” from the Fourth Edition of its Reference Manual on Scientific Evidence. The peer-reviewed guidance on climate science was removed in response to unfounded partisan pressure. The FJC has published the Manual since 1994 as a critical resource to assist judges in considering scientific evidence. It has been cited by the U.S. Supreme Court and thousands of other federal and state judges over its three decades in circulation. The Fourth Edition, published in December 2025, was the first edition to include a chapter on climate science. 

“We strongly oppose the Federal Judicial Center’s decision to erase climate science from the judicial manual — removing the climate science chapter doesn’t make the science any less real,” said Attorney General Bonta. “It is essential that judges have access to a reference manual with accurate and up-to-date science when making decisions that affect our environment and public health. California stands on the side of truth and science and urges the Federal Judicial Center to reverse course and stand with us.”

Prior to publication, each chapter of the Manual undergoes extensive peer-review over many months by the scientific community and by judges, who offer feedback that is then incorporated into the chapter. The Reference Guide on Climate Science chapter was treated no differently than any other chapter and was subjected to the same deliberate and thorough peer-review process. That process was thrown aside when the FJC decided, without any explanation or public process, to remove the chapter on climate science in response to partisan pressure.  

As the coalition states in the letter: “Such a guide is sorely needed as litigation involving climate science only grows in prevalence and urgency in our courts. Furthermore, the chapter’s removal does not change the scientific reality of climate change. As the U.S. Supreme Court acknowledged nearly twenty years ago, ‘[a] well-documented rise in global temperatures has coincided with a significant increase in the concentration of carbon dioxide in the atmosphere,’ a causal connection between man-made greenhouse gases and global warming exists, and ‘the harms associated with climate change are serious and well recognized.’ In light of this scientific fact, removing the climate science chapter only harms our judicial system, as judges and litigants are left without impartial, peer-reviewed information on complex and crucial scientific issues. This undermines the FJC’s statutory purpose ‘to further the development and adaptation of improved judicial administration in the courts of the United States.’”   

The coalition urges the FJC to reinstate the Reference Guidance on Climate Science chapter to the Manual.   

In sending the letter, Attorney General Bonta joined the attorneys general and chief legal officers of Arizona, Colorado, Connecticut, Delaware, the District of Columbia, Hawaii, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, Nevada, New Jersey, New Mexico, New York, Oregon, Rhode Island, Vermont, Virginia, Washington, Wisconsin, the Cities of New York and Chicago, and Harris County, Texas.