Citizen Suits Gain Ground: Supreme Court Denial Sparks New Compliance Risks for Industry

In a quiet but consequential move, the U.S. Supreme Court has denied review in two closely watched cases that could have narrowed the scope of citizen suit enforcement under the Clean Air Act (CAA) and Clean Water Act (CWA). The result? A green light for environmental groups to pursue more aggressive private enforcement—just as federal enforcement shows signs of retreat.

What Happened

On June 30, the Court declined to hear ExxonMobil Corp. v. Environment Texas Citizen Lobby and Port of Tacoma v. Puget Soundkeeper Alliance, effectively leaving in place two appellate rulings that affirm broad rights for citizen groups to bring environmental enforcement cases—even when state or federal regulators choose not to act.

What Industry Should Know

• Broader Standing for Citizen Plaintiffs: The Court’s decision leaves intact Friends of the Earth v. Laidlaw, a 2000 precedent that allows civil penalties paid to the government—not to plaintiffs—to satisfy Article III standing. This greatly expands the legal viability of citizen suits.

• Clean Air Act (ExxonMobil): The Fifth Circuit upheld nearly $15 million in penalties against Exxon’s Baytown facility for years of excess emissions. Industry had hoped the Court would revisit Laidlaw and limit civil penalties to injuries directly affecting plaintiffs.

• Clean Water Act (Port of Tacoma): The Ninth Circuit allowed citizen enforcement of state-issued stormwater permits—expanding citizen suit authority beyond federal minimum requirements. The ruling opens the door to suits targeting more stringent state-level mandates.

• No Circuit Split, No Cert: Despite support from over two dozen states and a push from the Trump administration’s solicitor general, the Court saw no circuit conflict requiring resolution. Legal observers view this as tacit affirmation of current lower court doctrine.

Why It Matters

Environmental groups are signaling a more aggressive posture, especially as the federal government scales back enforcement priorities. With maximum daily penalties exceeding $120,000 under the CAA and $68,000 under the CWA, the financial exposure from these suits is significant.

Law firms warn that:

• Notice of Intent to Sue letters should be treated as early warnings—companies must be prepared to respond promptly and strategically.

• Broader Use of Citizen Suit Tools under RCRA and CERCLA is likely as enforcement gaps widen.

Bottom Line

The door is wide open for increased citizen enforcement. While regulatory rollback efforts grab headlines, this development may have a more immediate impact on compliance risk. Companies operating in regulated sectors—especially those with aging permits or historical emissions—should re-evaluate their environmental compliance posture and be ready for the possibility of private federal enforcement.