Environmental Law Legal Terms Glossary
Explore definitions, related concepts, and supporting case briefs.
Definitions
NEPA
The National Environmental Policy Act of 1969 (42 U.S.C. 4321 et seq.) is the foundational federal environmental statute requiring all federal agencies to assess the environmental effects of their proposed actions before making decisions. NEPA does not mandate particular outcomes but imposes procedural requirements: agencies must prepare an Environmental Assessment (EA) or, for major federal actions significantly affecting the environment, a full Environmental Impact Statement (EIS). The Supreme Court in Robertson v. Methow Valley Citizens Council (1989) confirmed that NEPA is purely procedural, meaning an agency can proceed with an environmentally harmful action so long as it takes the requisite "hard look" at environmental consequences. NEPA is enforced primarily through judicial review under the Administrative Procedure Act, with courts examining whether the agency's environmental analysis was arbitrary and capricious.
Clean Air Act
The Clean Air Act (42 U.S.C. 7401 et seq.), originally enacted in 1963 and substantially amended in 1970 and 1990, is the comprehensive federal statute regulating air emissions from stationary and mobile sources. The Act directs the EPA to establish National Ambient Air Quality Standards (NAAQS) for criteria pollutants, requires states to develop State Implementation Plans (SIPs) to achieve those standards, and imposes New Source Performance Standards (NSPS) and hazardous air pollutant regulations. In Whitman v. American Trucking Associations (2001), the Supreme Court held that the EPA may not consider implementation costs when setting NAAQS, and that the Act's delegation of authority to EPA did not violate the nondelegation doctrine. The 1990 amendments introduced the Title IV acid rain cap-and-trade program, which became a model for market-based environmental regulation.
Clean Water Act
The Clean Water Act (33 U.S.C. 1251 et seq.), formally the Federal Water Pollution Control Act as amended in 1972, establishes the regulatory framework for discharging pollutants into navigable waters of the United States. The Act's core prohibition, Section 301, makes it unlawful to discharge any pollutant from a point source into navigable waters without a National Pollutant Discharge Elimination System (NPDES) permit issued under Section 402. Section 404 separately governs the discharge of dredged or fill material into wetlands and waterways, administered by the Army Corps of Engineers. The CWA sets a national goal of making all waters "fishable and swimmable" and authorizes EPA to establish technology-based effluent limitations and water-quality-based standards, including Total Maximum Daily Loads for impaired water bodies under Section 303(d).
CERCLA (Superfund)
The Comprehensive Environmental Response, Compensation, and Liability Act of 1980 (42 U.S.C. 9601 et seq.), commonly known as Superfund, establishes a federal program for cleaning up sites contaminated with hazardous substances and imposes strict, joint and several, and retroactive liability on potentially responsible parties (PRPs). PRPs include current owners and operators of contaminated facilities, past owners and operators at the time of disposal, generators who arranged for disposal of hazardous substances, and transporters who selected the disposal site. CERCLA liability is notoriously expansive: a PRP can be held liable for the entire cost of cleanup even if it contributed only a small fraction of the contamination, though it may seek contribution from other PRPs under Section 113(f). The Superfund trust, originally financed by taxes on petroleum and chemical industries, provides EPA with funds to clean up orphan sites where no viable PRP exists.
RCRA
The Resource Conservation and Recovery Act (42 U.S.C. 6901 et seq.), enacted in 1976, governs the management of hazardous and solid waste from generation through disposal, creating what is often called a "cradle-to-grave" regulatory system. RCRA Subtitle C establishes a comprehensive permitting and tracking regime for hazardous waste generators, transporters, and treatment, storage, and disposal facilities (TSDFs), requiring detailed manifests that follow waste from its point of origin to final disposition. Subtitle D addresses non-hazardous solid waste, primarily regulating municipal landfills, while Subtitle I governs underground storage tanks. Unlike CERCLA, which addresses past contamination at abandoned sites, RCRA is forward-looking and regulates the ongoing handling of waste to prevent future contamination, though Section 7002 allows citizen suits against parties contributing to an imminent and substantial endangerment from solid or hazardous waste.
ESA (Endangered Species Act)
The Endangered Species Act of 1973 (16 U.S.C. 1531 et seq.) is the primary federal law protecting imperiled species and their ecosystems, administered jointly by the U.S. Fish and Wildlife Service (terrestrial and freshwater species) and the National Marine Fisheries Service (marine species). Section 9 prohibits the "take" of any endangered species, defined broadly to include harassing, harming, pursuing, hunting, shooting, wounding, killing, trapping, capturing, or collecting, with "harm" further interpreted to encompass significant habitat modification that actually kills or injures wildlife. Section 7 requires all federal agencies to consult with FWS or NMFS to ensure that their actions are not likely to jeopardize the continued existence of listed species or destroy critical habitat. The Act's stringent protections were upheld in TVA v. Hill (1978), where the Supreme Court halted completion of a nearly finished dam to protect the snail darter, emphasizing that Congress intended endangered species protection to enjoy the highest priority.
Environmental Impact Statement
An Environmental Impact Statement (EIS) is the detailed written analysis required under Section 102(2)(C) of NEPA for any major federal action significantly affecting the quality of the human environment. The EIS must describe the proposed action, its purpose and need, the affected environment, the environmental consequences of the action, alternatives to the proposed action (including a "no action" alternative), and measures to mitigate adverse impacts. Courts review the adequacy of an EIS under the "rule of reason" standard, asking whether the agency took a "hard look" at environmental consequences rather than whether the agency reached the correct substantive result. The Council on Environmental Quality (CEQ) regulations require agencies to circulate a draft EIS for public comment before preparing the final EIS, making the process a key mechanism for public participation in federal decision-making.
Standing (Environmental)
Standing in environmental law requires plaintiffs to satisfy the three-part constitutional test from Lujan v. Defenders of Wildlife (1992): (1) injury in fact that is concrete, particularized, and actual or imminent; (2) a causal connection between the injury and the challenged conduct; and (3) a likelihood that a favorable judicial decision will redress the injury. Environmental plaintiffs must demonstrate more than a generalized grievance about environmental degradation; at least one organizational member must show personal use of or connection to the affected area. The standing doctrine has been particularly consequential in climate change litigation, where courts in cases like Massachusetts v. EPA (2007) have recognized that states may have special solicitude in standing analysis, while private plaintiffs face steeper hurdles in demonstrating particularized injury from diffuse environmental harms.
Citizen Suit
A citizen suit provision is a statutory mechanism found in virtually all major federal environmental statutes (including the Clean Air Act Section 304, Clean Water Act Section 505, RCRA Section 7002, and ESA Section 11) that authorizes private parties to bring enforcement actions against violators of environmental laws or against the EPA for failure to perform non-discretionary duties. Before filing suit, the plaintiff typically must provide 60 days' written notice to the alleged violator, the EPA, and the relevant state agency, allowing the government an opportunity to commence its own enforcement action, which can preempt the citizen suit. Citizen suits serve as a critical "private attorney general" enforcement supplement, enabling environmental groups and individuals to hold polluters accountable when government agencies lack resources or political will to enforce. Prevailing plaintiffs in citizen suits may recover attorney's fees and litigation costs, and courts may impose injunctive relief and civil penalties payable to the U.S. Treasury.
Polluter Pays Principle
The polluter pays principle is a foundational norm of environmental law holding that the party responsible for producing pollution should bear the costs of managing, remediating, and compensating for the environmental damage it causes, rather than shifting those costs to society at large. In U.S. law, this principle is most forcefully embodied in CERCLA's strict, joint and several, and retroactive liability scheme, which compels potentially responsible parties to fund the cleanup of hazardous waste sites regardless of fault or the lawfulness of their conduct at the time of disposal. The principle also underlies the structure of technology-based effluent standards under the Clean Water Act and emission standards under the Clean Air Act, which require polluters to internalize abatement costs. Internationally, the principle was endorsed in Principle 16 of the 1992 Rio Declaration and informs the design of emissions trading systems and pollution taxes worldwide.
Precautionary Principle
The precautionary principle holds that where an activity raises threats of serious or irreversible environmental harm, scientific uncertainty about the precise nature or magnitude of the harm should not be used as a reason to postpone cost-effective measures to prevent environmental degradation. Articulated in Principle 15 of the 1992 Rio Declaration, the principle shifts the burden of proof from those seeking to protect the environment to those proposing potentially harmful activities, requiring proponents to demonstrate safety rather than opponents to prove danger. While European Union environmental law explicitly incorporates the precautionary principle as a legal standard, U.S. environmental law applies it more implicitly through provisions like the Clean Air Act's requirement that NAAQS protect public health with an "adequate margin of safety" and FIFRA's precautionary approach to pesticide registration. The principle remains controversial in U.S. regulatory policy, with critics arguing it can stifle innovation and supporters contending it is essential for preventing catastrophic and irreversible environmental damage.
Cap and Trade
Cap and trade is a market-based regulatory mechanism that sets an aggregate limit (cap) on total emissions of a pollutant within a defined jurisdiction and distributes tradable allowances representing the right to emit a specified quantity, allowing regulated entities to buy and sell allowances to achieve compliance at the lowest overall cost. The seminal U.S. example is Title IV of the 1990 Clean Air Act Amendments, which established a sulfur dioxide (SO2) trading program to address acid rain; the program is widely regarded as having achieved emission reductions faster and at far lower cost than traditional command-and-control regulation. Under this system, firms that can reduce emissions cheaply will do so and sell surplus allowances to firms facing higher abatement costs, theoretically driving emissions reductions to their economically efficient level. Cap-and-trade programs have since been applied to greenhouse gases, most notably in the European Union Emissions Trading System and California's AB 32 program.
Best Available Technology
Best Available Technology (BAT) is a regulatory standard used across multiple environmental statutes requiring regulated facilities to employ the most effective pollution control technology that is economically achievable for a given industrial category. Under the Clean Water Act, BAT is the standard for controlling toxic and non-conventional pollutant discharges, with EPA determining what technology is "available" by examining the best-performing facilities in an industry and assessing whether the costs of adoption are reasonable relative to the effluent reduction achieved. The Clean Air Act employs analogous concepts including Best Available Control Technology (BACT) for new sources in attainment areas and Lowest Achievable Emission Rate (LAER) for new sources in nonattainment areas. BAT standards are "technology-forcing" in nature, meaning they push industry toward continual improvement rather than freezing pollution control at current levels, and they are periodically revised as new technologies emerge.
Total Maximum Daily Load (TMDL)
A Total Maximum Daily Load (TMDL) is a calculation of the maximum amount of a specific pollutant that a water body can receive and still meet applicable water quality standards, as required under Section 303(d) of the Clean Water Act. States must identify water bodies that fail to meet water quality standards even after point sources have implemented technology-based controls, place them on the 303(d) impaired waters list, and develop TMDLs that allocate permissible pollutant loads among point sources (as waste load allocations) and nonpoint sources (as load allocations), with a margin of safety. TMDLs are significant because they represent one of the few mechanisms under the CWA for addressing nonpoint source pollution (such as agricultural runoff), which is otherwise largely unregulated at the federal level. EPA must approve or disapprove state-submitted TMDLs and may establish its own TMDLs if a state fails to act, making the TMDL program a frequent subject of litigation by environmental groups seeking to compel action on impaired waters.
Brownfield
A brownfield is real property where expansion, redevelopment, or reuse may be complicated by the presence or potential presence of a hazardous substance, pollutant, or contaminant, as defined by the Small Business Liability Relief and Brownfields Revitalization Act of 2002 (amending CERCLA). Brownfield sites are distinguished from Superfund sites in that they typically involve lower levels of contamination that do not warrant listing on the National Priorities List but still deter private investment due to fear of CERCLA liability. The brownfields program provides EPA grants, tax incentives, and liability protections (including bona fide prospective purchaser, contiguous property owner, and innocent landowner defenses) to encourage voluntary cleanup and productive reuse of contaminated properties. Brownfield redevelopment represents a policy shift from the punitive liability focus of early CERCLA enforcement toward incentive-based approaches that balance environmental remediation with economic revitalization of blighted urban and industrial areas.