This educational guide is based on the linked primary sources. It is not a Court publication, is not affiliated with the Court, and is not legal advice.
In brief
Overview
According to Environmental Protection Agency, the Environmental Protection Agency has for more than 30 years interpreted the Clean Water Act to permit consideration of costs and benefits when setting limits on water intake.
According to Petitioners, petitioners note that the Executive Branch has required a cost‑benefit analysis for regulations for almost 30 years.
According to Environmental Protection Agency, the EPA argues that the Riverkeeper 1 decision is inconsistent with other opinions and demonstrates ambiguity in the law.
According to Environmental Protection Agency, ePA’s cost‑benefit analysis was not among the most robust forms; it first created national performance standards.
According to Environmental Protection Agency, ePA also applied a variance when a facility’s costs were significantly greater than the benefits.
Background and question before the Court
The central question is whether the EPA may consider costs when determining the “best technology available” under Clean Water Act section 316(b).
What each side argues
Petitioners’ Position (Entergy Corp, PSEG Fossil LLC, Utility Water Act Group)
Petitioners argue that cost‑benefit analysis is a longstanding requirement for regulations and should be considered in the EPA’s rulemaking.
Petitioners (Mr. Lazarus) contend that Section 316(b) does not authorize the EPA to weigh costs against benefits; Congress excluded cost‑benefit analysis and focused on technology availability.
According to Mr. LAZARUS, petitioners assert that “availability includes economic availability.”
According to Mr. LAZARUS, petitioners claim that the “best available” standard does not involve a cost‑benefit analysis, only a “best practical” approach.
Riverkeeper, Inc. Position
Source-limited. The record does not yet support a complete account.
What happened at oral argument
According to Chief Justice Roberts, chief Justice Roberts opened the argument for Case 07‑588.
Justice Breyer asked whether the petitioners were arguing that costs should be taken into account.
According to Justice Ginsburg, justice Ginsburg questioned how much cost consideration is appropriate and noted concerns about comparing incomparable factors.
Justice Souter asked whether the cost question was merely about the industry’s economic ability to afford the technology.
According to Justice Scalia, justice Scalia inquired whether Section 307 allowed a cost‑benefit analysis.
Justice Alito asked how cost could be incorporated into the concept of availability.
According to Chief Justice Roberts, chief Justice Roberts queried whether the panel’s decision overruled the prior Riverkeeper 1 decision.
- [1] 6bb1b48a70ec8cc0a504-r1-ade17efb97f08f98.pdf, p. 4
- [2] 6bb1b48a70ec8cc0a504-r1-ade17efb97f08f98.pdf, p. 21
- [3] 6bb1b48a70ec8cc0a504-r1-ade17efb97f08f98.pdf, pp. 9–10
- [4] 6bb1b48a70ec8cc0a504-r1-ade17efb97f08f98.pdf, p. 42
- [5] 6bb1b48a70ec8cc0a504-r1-ade17efb97f08f98.pdf, p. 57
- [6] 6bb1b48a70ec8cc0a504-r1-ade17efb97f08f98.pdf, p. 31
- [7] 6bb1b48a70ec8cc0a504-r1-ade17efb97f08f98.pdf, p. 58
What the Court decided
Why it matters
Terms to know
No glossary terms are available for this guide.
Primary sources
Read the source materials on the official site or open the immutable repository copy used for this guide.
- 6bb1b48a70ec8cc0a504-r1-ade17efb97f08f98.pdforal argument transcript
Guide generated September 22, 2026. Automated validation accepted this version.