EPA Moves Against California Harbor Craft Rule
California’s Commercial Harbor Craft (CHC) regulation, a long-time bane of the maritime industry that requires most commercial harbor craft to attach expensive, untested and (the marine industry claims) unworkable diesel particulate filters (DPFs) to marine engines to operate legally, has been referred to Congress for review by the Environmental Protection Agency. The move is part of a multi-front war being waged by President Donald Trump’s administration, and in Congress, against California’s unique power to set emissions policy, based on a special waiver from the 1970 Clean Air Act.
DPFs have become standard equipment on most new car and truck engines, but workable DPFs for marine engines have not yet been designed. The variable temperatures at which towing vessel engines operate make their use a problem, since DPFs require very high temperatures to incinerate particulate pollution. Retrofit options for commercial towing vessels remain scarce. The market for DPFs for commercial harbor vessels and towing remains too small to justify expensive research and development costs.
On July 22, the EPA posted, “In accordance with the Congressional Review Act (CRA), U.S. Environmental Protection Agency (EPA) transmitted two more California waiver rules to Congress that have given the state the authority to enact its own emission standards for marine vessels and ports critical to America’s supply chain for essential goods. EPA has determined that each of these waivers is a rule under the CRA, and because the previous administration failed to transmit them to Congress, as mandated under the CRA, Congress has not been provided with its statutorily required opportunity to review these rules. Today’s action follows EPA’s June 2026 transmittal of four California waiver rules pertaining to California’s emission standards for cars, trucks, lawn mowers and other equipment used daily by Americans.”
EPA Administrator Lee Zeldin said, “EPA is once again fulfilling our statutory obligation to submit California waiver rules to Congress. This is what the law requires, and it is our obligation to the American people to follow the best reading of the law every single time. This is how we remain accountable to all Americans, instead of picking winners and losers like previous administrations.”
The action against the CHC rule could pave the way for a federal override of the California Air Resources Board’s (CARB) marine DPF regulation. Repeated efforts by maritime interests to get California to reverse or soften the rule have failed. California Gov. Gavin Newsom vetoed a bill to repeal it that passed by a near-unanimous bipartisan vote in the California legislature.
Marine Emissions Rules
The purpose of CARB’s CHC regulation was to severely reduce or eliminate particulate emissions. The CHC rule was initially drafted in 2007 but didn’t become fully effective in its final form until January 1, 2023. DPFs act like mini-furnaces, recirculating hot exhaust gases to incinerate particulate matter in a process called regeneration. In the regeneration process, peak internal temperatures can briefly reach upwards of 1,472 degrees Fahrenheit to 2,012 degrees Fahrenheit. The Coast Guard, responsible for safety aboard vessels, has stated it refuses to accept, recognize or certify marine DPFs. When DPF mandates for California truck engines kicked in early in the 2000s, truck DPFs bursting into flames caused a number of publicized fires, including one that became a wildfire.
Along with the CHC rule, the EPA also submitted for federal review another CARB rule drafted in 2007, the At Berth rule, which, like the CHC, was updated and expanded in several stages. It was designed to cut vessel emissions from docked ships, with a goal of moving toward net zero. It requires docked vessels to turn off onboard generators and plug into shore-based power sources.
California’s Waiver Authority
Congress gave California (but no other state) special waiver authority under the Clean Air Act (1970) to set its own pollution and emission regulations—but only if they were stricter than federal regulations. This was originally in response to what was then believed to be an especially serious smog problem in Los Angeles. Later, Congress allowed other states to adopt California’s emissions standards, but not to develop their own; they could only choose between federal standards or California’s. To date, 17 states have adopted California’s.
California’s Air Resources Board (CARB) gradually became one of the most powerful agencies in the state and nationwide. Because California was such an important car market, Detroit automakers essentially let CARB set car emissions standards for years.
CARB’s authority derives from the waiver granted by Congress. What Congress gives, Congress can take away — in theory. But for more than 50 years, past Congresses rarely challenged or restricted CARB’s authority and looked favorably on the idea of CARB being able to pioneer emissions standards for the rest of the country. Under previous leaders and administrations, the EPA has granted California more than 100 specific waivers to set its own emissions standards that apply to various chemicals and substances.
Courts have mostly upheld the legality of this federal preemption waiver. For example, a major challenge to the 2022 reinstatement of California’s Clean Cars waiver was dismissed by the D.C. Circuit Court of Appeals.
Expansion And Pushback
In 2006, CARB’s regulatory authority was expanded by the Global Warming Solutions Act of 2006 (AB 32) to include greenhouse gases rather than just “pollutants” (substances that directly harmed humans through exposure). It ordered CARB to reduce emissions from all sources to 1990 levels by 2020. A year later, the U.S. Supreme Court, in the landmark Massachusetts v. EPA case, also ruled that greenhouse gases could be regulated as “pollutants.” Since virtually every activity emits greenhouse gases, the redefinition of “pollutant” to include greenhouse gases greatly expanded the powers of both CARB and the EPA to regulate the entire economy.
That expanded mandate led to an aggressive push under President Joe Biden and a Democratic-controlled Congress to severely reduce or eliminate carbon emissions and to move toward net zero. California began drafting rules to incentivize a transition away from internal combustion engines to electric vehicles. The Inflation Reduction Act of 2022 included $369 billion in tax credits and incentives to encourage electric vehicle production.
Multi-Front War
The recent EPA action is part of a multi-front legal and administrative war the Trump administration is fighting to claw back or halt many of California’s zero emissions rules and initiatives and reset the boundaries of state versus federal authority to regulate emissions. On March 12, the Department of Justice sued the California Air Resources Board, seeking to overturn California’s carbon dioxide tailpipe emissions standards and zero-emissions vehicle sales mandates. The federal government now argues that individual states do not have the right to set regulations that intersect with federal fuel economy standards.
In Congress, Republicans have been waging their own war against the waiver and CARB. In March 2025, the Stop CARB Act, which sought to entirely revoke California’s Clean Air Act waiver, was re-introduced in Congress after having been introduced in 2024.
Congressional Review Act
Another pathway is being pursued against the waiver and CARB’s authority. The Congressional Review Act is a rarely-used (until recently) check on California’s waiver authority to pre-empt federal rules. It allows Congress to revisit and revoke federal agency rulemaking actions by requiring all final rules to be submitted to Congress. More importantly, it allows any member of Congress to introduce a joint resolution disapproving an agency’s final rule.
A CRA resolution passed by Congress and signed by the president has the force of federal law and prevents the rule from going into effect. Furthermore, no revoked agency rule can be reissued by a federal agency in the same or “substantially similar” fashion.
However, Congress’ authority to approve or revoke actions by CARB applies only to “final rules” as defined under the Administrative Procedures Act (APA), which sets standards for federal rule-making. Defenders of CARB’s actions argue that agency actions like the Commercial Harbor Craft Rule are “orders” or “decisions” rather than “rules.” The distinction may sound arcane, but it is crucial. Previous administrations, both Republican and Democratic, treated such actions as orders not subject to review by Congress, but Trump’s EPA has reclassified them as rules.
On June 25, California sued the EPA in the U.S. District Court for the District of Columbia to overturn the reclassification, arguing that it violates the APA and was enacted without proper public notice. The state asked for a preliminary injunction or stay.
The results of the several court cases and congressional bills now underway will determine the new boundaries of state versus federal authorities in regulating emissions.
