The Environmental Protection Agency (EPA) is transmitting to Congress for review two major truck rules from the California Air Resources Board (CARB) that received waivers from EPA under the Biden Administration.

CARB’s Advanced Clean Trucks rule and its Omnibus NOx rule will be subject to congressional review and potentially disapproval under the Congressional Review Act, which prevents agency regulations from going into effect if a majority of each house of Congress passes a “resolution of disapproval” and the resolution is signed by the President.

EPA granted a waiver to CARB for the ACT rule in 2023 and granted a waiver for the NOx rule in December 2024, but neither action was submitted to Congress as required by the Act. The Biden Administration believed that EPA waivers are not subject to the Congressional Review Act because they are not “rules” as defined in the Administrative Procedure Act. The Trump Administration has taken the opposite view.

If Congress passes the resolutions of disapproval, as expected, neither the ACT nor the NOx rule could be enforced in California or in other States, including Maryland, Massachusetts, New Jersey, New York, Rhode Island, and Vermont. It would nullify implementation in those states where the rule has already gone into effect. But the issue of whether EPA waivers are subject to the Congressional Review Act will likely be decided by the courts.