Department of Transportation v. Public Citizen, 541 U.S. 752 (2004)
Department of Transportation v. Public Citizen is a cornerstone Supreme Court decision on the scope of an agency's obligations under the National Environmental Policy Act (NEPA).
Does NEPA require FMCSA to prepare an EIS or otherwise consider environmental impacts allegedly resulting from increased cross-border operations of Mexican motor carriers where FMCSA lacks statutory authority to prevent those effects, and does the Clean Air Act's general conformity provision require a conformity determination under these circumstances?
NEPA requires an EIS for major federal actions significantly affecting the human environment, but an agency need only consider environmental effects for which it is a legally relevant cause—i.e., effects with a reasonably close causal relationship to the agency's action—and that the agency has statutory authority to prevent or mitigate. NEPA does not mandate consideration of environmental impacts that flow from decisions of actors outside NEPA's scope (such as the President) or from legal directives that leave the agency without discretion to deny or condition the action on environmental grounds. Similarly, under the Clean Air Act's general conformity provision, 42 U.S.C. § 7506(c), a conformity determination is required only for federal actions that cause or contribute to emissions in nonattainment or maintenance areas and over which the agency has sufficient discretion or control; where the agency lacks authority to prevent the emissions, a conformity determination is not required.
No. FMCSA did not violate NEPA or the Clean Air Act. Because FMCSA lacked authority to prevent the cross-border operations causing the alleged environmental effects—and because those effects resulted from the President's decision to lift the moratorium—NEPA did not require an EIS or EA, and the Clean Air Act's general conformity provision did not apply. The Supreme Court reversed the Ninth Circuit.
Public Citizen is a leading case delineating the outer bounds of NEPA's reach. It clarifies that NEPA review is required only for environmental effects an agency's action legally causes and that the agency has authority to influence. This "no discretion, no EIS" principle prevents courts from compelling superfluous environmental analyses when an agency cannot lawfully deny or modify the action on environmental grounds. For law students, the decision is essential for understanding how courts evaluate causation and discretion in NEPA litigation, how presidential or congressional directives can constrain agency obligations, and how CEQ regulations operate within—rather than expand beyond—statutory limits. It also informs Clean Air Act conformity analysis by emphasizing the need for an agency nexus to emissions the agency can control.