H.R.9618

DEF Act Diesel Engine Flexibility Act

Introduced·7/9/26

The DEF Act aims to maintain regulatory stability for motor vehicles and engines by limiting stringent emissions standards.

The DEF Act, or Diesel Engine Flexibility Act, amends the Clean Air Act to ensure regulatory stability for motor vehicles and engines. It prohibits the Environmental Protection Agency from implementing more stringent emissions standards for on-road and nonroad vehicles and engines for ten years. During this period, the EPA can only promulgate standards that apply for at least three model years and take effect five years after promulgation. The Act also provides a safe harbor for certain emissions control strategies if implemented according to specified guidance documents.

Included in complete analysis

  • Overview
  • Core Provisions
  • Implementation
  • Impact
  • Legal Framework
  • Critical Issues

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Where it stands

Current
In committee
Next
Committee decision

Sponsors

Democratic CaucusRepublican Caucus

History

Jul 14

House

Subcommittee Consideration and Mark-up Session Held

Jul 14

House

Forwarded by Subcommittee to Full Committee by Voice Vote.

Jul 9

House

Introduced in House