How the federal diesel-emissions system was built

Regulatory and enforcement chronology

Statutes, regulations, EPA rulemakings and DOJ policy that structure the federal diesel-emissions system — with direct links.

• 42 U.S.C. § 7521 — Motor vehicle emission and fuel standards

  Statute · Neutral background

• 42 U.S.C. § 7522 — Prohibited acts (tampering)

  Statute · Neutral background

• 42 U.S.C. § 7524 — Civil penalties

  Statute · Neutral background

• 42 U.S.C. § 7413(c) — Criminal penalties

  Statute · Neutral background

• Clean Air Act § 306 (42 U.S.C. § 7606) — Federal procurement

  Statute · Neutral background

• Clean Air Act § 209 (42 U.S.C. § 7543) — California waiver authority

  Statute · Neutral background

• 40 CFR Part 1036 — On-Highway Heavy-Duty Highway Engines

  Regulation · Neutral background

• 40 CFR 1036.111 — Diagnostic and inducement requirements

  Regulation · Neutral background

• 40 CFR Part 1039 — Control of Emissions from New and In-Use Nonroad Compression-Ignition Engines (Tier 4)

  Regulation · Neutral background

• Control of Air Pollution From New Motor Vehicles: Heavy-Duty Engine and Vehicle Standards (2027 rule)

  Federal Register notice · January 24, 2023 · Supports current regime

• Proposed amendments to heavy-duty highway and nonroad diesel provisions (Docket EPA-HQ-OAR-2026-0728)

  EPA rulemaking · 2026 · Supports repeal or revision

• National Compliance Initiative — Stopping Aftermarket Defeat Devices

  EPA guidance · Supports current regime

• DOJ policy — deprioritization of criminal defeat-device prosecutions

  DOJ policy · 2025 · Supports repeal or revision

• EPA Annual Enforcement and Compliance Results

  Government report · annual · Supports current regime

• Civil Monetary Penalty Inflation Adjustment Rule — Clean Air Act mobile-source penalties

  Federal Register notice · annual · Neutral background

Read the underlying history

Nonpartisan and academic accounts of how federal air-pollution authority developed. Read these before drawing conclusions about today's diesel program.