DEF Act

Bill Number

H.R. 9618

Origin Chamber

House

Congress

119th Congress, Session 2

Status

Introduced

Latest Action

2026-07-09: Referred to the House Committee on Energy and Commerce.

Last Updated

2026-07-10T10:23:22Z

AI-Generated Summary

Purpose of the legislation This bill amends the Clean Air Act to establish a 10-year period of regulatory stability for on-road and nonroad diesel engines. It aims to limit the Environmental Protection Agency’s (EPA) ability to impose stricter emissions standards during this time while allowing certain compliance practices described in agency guidance documents.

Key provisions outlined

• Section 2 (On-road vehicles and engines): Adds subsection (n) to Section 202 of the Clean Air Act. It creates a 10-year safe harbor (starting from enactment) for inducement strategies and diesel exhaust fluid (DEF) quality monitoring consistent with specified EPA guidance documents for vehicles and engines meeting 2007 or 2010 standards. The EPA may not issue regulations more stringent than those standards during this period, with limited exceptions for software updates, enforcement against defeat devices, and voluntary actions. After the 10-year period, any new or revised standards must apply for at least 3 model years and take effect no earlier than 5 years after promulgation. The EPA must consider factors such as operational disruption, engine durability, resale value, costs to owners, national consistency, and harmonization across categories.
• Section 3 (Nonroad vehicles and engines): Adds subsection (e) to Section 213 of the Clean Air Act with parallel provisions. It provides a 10-year safe harbor for inducement strategies, repair-related overrides, and DEF monitoring consistent with the listed guidance for engines meeting Tier 4 standards. The same temporary freeze on stricter rules, lead-time requirements, and required considerations apply, with additional guidance documents referenced for nonroad equipment.
• Rule of construction: The bill explicitly does not authorize permanent disablement of emissions controls or exempt engines from existing standards.
• Definitions: References specific EPA guidance documents (e.g., IACD-2025-10, IACD-2026-05) and standards (2007/2010 for on-road; Tier 4 for nonroad) as they existed on January 1, 2025.

Significant changes to existing law introduced The bill adds new subsections to the Clean Air Act that temporarily restrict the EPA’s authority to promulgate or implement more stringent emissions standards under Sections 202 and 213 (and related waiver provisions under Section 209). It introduces mandatory lead-time and consideration requirements for future standards and provides safe-harbor protections tied to specific guidance documents.

Potential impacts on government agencies, citizens, or international relations

• Government agencies: Limits the EPA’s regulatory flexibility for 10 years, potentially reducing its ability to address emerging emissions issues or align with new technologies.
• Citizens: Provides greater predictability for owners and operators of diesel vehicles and equipment by reducing the risk of sudden stricter requirements, derates, or shutdowns, which may lower compliance and maintenance costs.
• International relations: No direct provisions address international agreements or trade; however, the emphasis on national consistency could indirectly affect harmonization with standards in other countries.

Main stakeholders affected by this legislation

• EPA (as the primary regulator whose actions are constrained).
• Manufacturers of on-road heavy-duty and light-duty diesel engines and vehicles.
• Manufacturers of nonroad compression-ignition engines and related equipment (e.g., construction, agricultural, and industrial machinery).
• Owners and operators of diesel-powered vehicles and equipment (including trucking, farming, and construction industries).
• Dealers and suppliers involved in equipment inventories and financing.

Notable legal, constitutional, or political implications The legislation represents a congressional limit on agency discretion under the Clean Air Act, potentially raising questions about the balance of power between the legislative and executive branches in environmental regulation. It may delay future emissions reductions, which could have implications for air quality goals. The bill does not alter constitutional authority over interstate commerce or environmental protection but codifies specific policy preferences for regulatory stability over the next decade.

This summary was generated by AI and may contain inaccuracies. Refer to the official source document for the authoritative text.

Sponsor

Rep. Fedorchak, Julie [R-ND-At Large]

Cosponsors (4)

Rep. Davis, Donald G. [D-NC-1], Rep. Finstad, Brad [R-MN-1], Rep. Bergman, Jack [R-MI-1], Rep. Fischbach, Michelle [R-MN-7]

Recent Actions

• 2026-07-09: Referred to the House Committee on Energy and Commerce.
• 2026-07-09: Introduced in House
• 2026-07-09: Introduced in House

Bill Versions

• Diesel Engine Flexibility Act — issued 2026-07-09 — PDF (15 pages)