Despite five decades of administrative practice and judicial development, there is a considerable gap in legal and empirical study on the impacts of the National Environmental Policy Act of 1970 (NEPA). Proponents of NEPA reform often claim that environmental litigation is a major obstacle for important federal actions. Others have studied the same issue and concluded that NEPA litigation is not a major contributor of project cost escalation or delays. This study addresses this gap by supplementing a data set of the largest 355 transportation and energy infrastructure projects in the United States which completed a federal environmental study between 2010 and 2018.

We observe predevelopment litigation on 28% of the energy and transport projects requiring an Environmental Impact Statement, 89% of which involve a claim of a NEPA violation. Of the major sectors, the highest litigation rate is in solar energy projects, nearly two-thirds of which are litigated. Light Rail Transit projects are litigated at nearly twice the rate of new highway projects and 2.5x the rate of highway improvement projects. Other high-litigation sectors include pipelines (50%), transmission lines (31%), and wind energy projects (38%). Energy sectors with higher rates of private financing have shorter permit durations, higher rates of litigation, and higher rates of cancellation but also higher completion rates relative to transport sectors, which have higher rates of public financing and lower rates of litigation, but extremely long permit timelines. Our findings shed additional light on the ways that NEPA impacts large, environmentally impactful infrastructure projects in various sectors in the United States.