Nebraska AG Hilgers Leads Challenge to Federal Judges' Reference Manual

LINCOLN, Neb. — Nebraska Attorney General Mike Hilgers joined a multi-state effort to challenge what Republican officials characterized as bias in a federal reference manual used by judges evaluating scientific evidence in court cases.

Hilgers led the charge in requesting an investigation into the Federal Judicial Center's "Reference Manual on Scientific Evidence," according to an announcement from his office. The Nebraska attorney general led a 22-State coalition in sending a letter to Congress that requests an investigation into how the Federal Judicial Center's most recent "Reference Manual on Scientific Evidence" attempts to improperly influence federal proceedings regarding scientific issues.

While the Reference Manual historically has described basic principles of science, the new Fourth Edition affirmatively takes a stance on major issues percolating in climate-related litigation. Hilgers said it "appears to embed the views of climate activists and diversity, equity, and inclusion ideologues into what is presented as neutral guidance."

According to Hilgers, "When the same advocates and experts who are actively litigating climate cases help write and review a chapter that will be used by federal judges behind the scenes, it raises obvious and serious concerns about the impartiality of the judicial system."

The Reference Manual on Scientific Evidence is a guide that judges use when managing cases that involve complex scientific and technical evidence during the description of evidence. In early February 2026, the Federal Judicial Centre removed a chapter explaining climate science from the Reference Manual on Scientific Evidence, with judges using this manual to evaluate scientific testimony in U.S. courtrooms.

The decision to remove the climate chapter in the reference was led by West Virginia Attorney General JB McCuskey and Nebraska Attorney General Mike Hilgers. Hilgers called the outcome a "huge win" on social media, saying he was "proud to work on this with [McCuskey] and our Republican AGs."

However, the removal has drawn criticism from the scientific community. Following the removal of the chapter, 28 co-authors of the Reference Manual issued an open letter calling the removal a "political attack," stating that "Omitting the climate science chapter from the Reference Manual deprives judges of a carefully reviewed baseline explanation of the relevant science. It leaves judges without a tool to evaluate the parties' framing, sometimes cherry-picked literature, and adversarially hired and paid witnesses."