Prohibits taxpayer resources from being used to enforce federal laws governing emissions control equipment on diesel engines

2026 Regular Session Introduced by Scott Cupps

Missouri bans enforcing federal rules removing diesel emission controls and lets individuals sue, with penalties on government actors and penalties to employers for employees’ viol

Referred: Emerging Issues(H)

#environmentalprotection #federal-staterelations #motorvehicles #statedepartments

Summary of HB 3515 (Missouri, 2026)

Purpose and intent

Prohibits any entity or public official in Missouri from enforcing or attempting to enforce federal laws, orders, or rules that govern the removal of emissions control devices on diesel-powered vehicles.

Creates civil liability and penalties for individuals and entities that act to enforce such federal emissions-related requirements under color of federal or state law.

Key provisions and changes

Definitions:

Introduces a new section (Section 1.371) defining “diesel-powered vehicle” to include a broad list of diesel-powered vehicle types (e.g., automobile transporter, boat transporter, bus, commercial motor vehicle, farm tractor, school bus, shuttle bus, truck/truck-tractor, log trucks, recreational vehicle, etc.).

Prohibition on enforcement:

No entity or person (including public officers or state/local government employees) may enforce or attempt to enforce any federal acts, laws, orders, regulations, or ordinances that govern the removal of emission control devices on diesel-powered vehicles.

Civil liability for enforcement:

If someone knowingly violates the prohibition, the injured party may sue for relief (action at law or equity).
Prevailing party (excluding the state of Missouri or its political subdivisions) may be awarded reasonable attorney’s fees and costs.
Sovereign, official, or qualified immunity is not an affirmative defense in such actions.

Civil penalties on government actors:

Any federal-acting official or employee within Missouri who knowingly enforces or assists in enforcing the described federal actions (or provides material aid) is subject to a civil penalty of $100,000 per occurrence.

Standing and judicial remedies:

Residents or businesses in a jurisdiction may sue for declaratory judgment in the circuit court where the action occurred or in Cole County regarding the actions of the individual.
If a court finds a violation, the employing entity must pay court costs and the employee’s attorney’s fees associated with the declaratory judgment action.

Who would be affected

Public officers and employees at the state, county, and local levels.

Any entity employing individuals who might enforce federal emissions-related laws on diesel-powered vehicles.

Private individuals or businesses who might be affected by enforcement actions or who seek relief through litigation.

The bill assigns liability to employers for violations by their employees acting under color of law.

Procedural and timeline aspects

Status: Referred to Emerging Issues (H) as of May 15, 2026.

Earlier actions include introduction and first reading in February 2026 and second reading in March 2026.

If enacted, the bill would operate prospectively, applying to actions occurring after passage.

Notable details

The bill mirrors concepts from a prior proposal (HB 1486, 2025) and includes explicit penalties and costs shifting.

It does not provide immunity defenses for the responsible actor, reinforcing accountability.

The civil penalty is imposed on the employer for violations by the employee acting under color of federal law.

Practical implications

Potential chills on federal enforcement efforts in Missouri related to emissions-control device removals on diesel vehicles.

Increased risk for public employers if they authorize or fail to prevent enforcement actions that run afoul of the prohibition.

A new avenue for private citizens and businesses to seek declaratory relief and recover fees if they believe enforcement occurred.