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We reviewed thirteen years of National Environmental Policy Act (“NEPA”) litigation data summarizing 1,499 federal court opinions to assess:

(1) How frequently NEPA compliance efforts result in litigation;

(2) how agency NEPA decisions fare in court; and

(3) how NEPA litigation outcomes compare to outcomes in other challenges to federal agency decisions.

We found that only one in 450 NEPA decisions were litigated and that the rate of NEPA challenges declined during the thirteen-year study period. We noted an inverse relationship between the amount of time spent on Environmental Impact Statement (“EIS”) preparation and the likelihood that an EIS would be challenged in court. We also found that while federal agencies prevail in NEPA litigation at slightly higher rates than in other civil cases where the government is a defendant, environmental plaintiffs win at higher rates than any other class of NEPA challengers. Overall, we conclude that the NEPA litigation burden may be overstated because few decisions are challenged in court, the rate of challenge is declining, and environmental plaintiffs are likely to bring only cases where they have a high likelihood of success. We therefore recommend against imposing strict deadlines and page limits on EISs as these “reforms” may do little to reduce the NEPA compliance burden while limiting opportunities for public engagement.