California – as part of effort to reduce the environmental impact of maritime shipping, particularly within vulnerable port-side communities – has implemented one of the most ambitious port-emission control programs to date.
California’s At-Berth Regulation (ABR), implemented in 2007, is a key environmental policy created to reduce air pollution from nonvehicular sources. Since 2014, the California Air Resources Board (CARB) has enforced the ABR for container ships, reefer ships, and passenger ships, requiring the use of shore power or CARB-approved emission control/capture systems while at port.
Before the implementation of the ABR, ocean-going vessels would typically run auxiliary diesel engines as an onboard power system to support lighting, refrigeration, ventilation, etc., while docked. These engines produce air contaminants such as nitrogen oxides, reactive organic gases, and particulate matter, which have been linked to various health issues such as heart and lung disease. These pollutants were found to disproportionately affect port workers and communities near California ports, many of which are designated as disadvantaged. The two compliance methods proposed by CARB, vessel use of emission-controlled systems or onshore grid electricity (also known as ‘cold ironing’), significantly reduce noise and air pollution.
In January, the ABR began a compliance phase in process to include tanker and RORO vessels, requiring them to implement a CARB Approved Emission-Control Strategy (CAECS) while berthed in California ports. Currently, the ABR only requires tanker vessels to utilize a CAECS when berthed at regulated terminals at Port of Los Angeles or Port of Long Beach, however, this will change to include all regulated terminals in January 2027.
While some vessel types were already accessing shore power while at berth, capture and control systems for tankers were not yet fully developed or approved at the time of regulation adoption. In response to the ABR’s 2025 inclusion of tanker vessels, the Western States Petroleum Association (WSPA) expressed its concern that the current infrastructure of the California tanker fleet is not equipped to access shore power. Furthermore, WSPA argued that the necessary technology needed to implement safe and reliable emission-control systems on board the fleet is not currently available.
In February, the WSPA challenged the ABR claiming that, (1) CARB acted arbitrarily and capriciously by setting technologically infeasible compliance deadlines; (2) CARB violated the Administrative Procedure Act (APA) by delaying public disclosure of a commissioned emissions study; and (3) CARB failed to comply with the California Environmental Quality Act (CEQA) by inadequately analyzing safety hazards and cumulative environmental impacts. The Court of Appeal found in favor of CARB, stating that there was substantial evidence supporting CARB’s conclusion that the required emissions control technologies were achievable by the compliance deadlines, and that the ABR complied with both the CEQA and the APA.
Despite industry resistance, California’s At-Berth Regulation continues to serve as a prominent example of state-level efforts to address maritime air pollution through regulatory action. As the 2027 compliance deadline approaches, effective implementation will require sustained coordination among regulators, industry stakeholders, and technology developers to ensure a practical and effective outcome. With no centralized federal authority overseeing port emissions, other states are likely to closely observe California’s approach as a potential model for future maritime environmental policy.