⚖ Oral Arguments, with Context

The D.C. Circuit considers competing challenges to a federal rule on ship pollution. Ships take in ballast water to maintain balance and stability as cargo changes. When they release that water elsewhere, they can also release living organisms carried from another place, potentially spreading invasive species. Congress passed the Vessel Incidental Discharge Act in 2018 to replace a patchwork of discharge requirements with a national framework. EPA sets pollution-control standards; the Coast Guard develops implementing rules. EPA published the rule challenged here in October 2024. The challengers petitioned the court directly to review that agency action, rather than appealing a trial about one pollution incident. The first part concerns Lakers: vessels operating exclusively in the Great Lakes region. EPA exempted this fleet from numeric ballast-water limits, citing difficult operating conditions. But it required covered new Lakers to install, operate, and maintain treatment equipment. Existing Lakers were not given that equipment requirement, although other management requirements still apply. The Lake Carriers' Association will argue that EPA lacks authority to impose this equipment mandate and did not adequately establish that the systems will work on these ships. Environmental groups take the opposite position on older Lakers: they say EPA failed to justify leaving them without the equipment requirement. Michigan and supporting states also challenge the removal of an earlier precaution against taking in ballast water in high-risk conditions. Best management practices are pollution-prevention measures; whether that term permits a major equipment mandate is disputed here. Best available technology economically achievable is a standard involving technology, engineering, and costs. Anti-backsliding generally bars weaker requirements, subject to specified exceptions, including previously unavailable information or a material technical mistake. The panel will ask what the statute authorizes and whether EPA reasonably explained its choices. Varu Chilakamarri will argue first for the carriers. Wendy Bloom will speak for the environmental groups. Elizabeth Morrisseau, a Michigan Assistant Attorney General, will address the uptake issue for the supporting states. Alex Hardee will defend EPA's rule. Later, the hearing turns to California's separate challenges.

Lake Carriers' Association v. EPA (No. 25-1027) — U.S. Court of Appeals for the D.C. Circuit, argued October 23, 2026.