AR SB478

Creates the "Arkansas Diesel Engine Freedom Act of 2025" prohibiting state enforcement of federal regulations requiring diesel exhaust fluid for diesel engines operated solely within Arkansas

Declares federal diesel exhaust fluid mandates unconstitutional under the Tenth Amendment for vehicles not engaged in interstate commerce, making such regulations "null and void" in Arkansas

Defines "exempt engines" as diesel engines operated solely within the state that do not require diesel exhaust fluid, and legalizes their manufacture, sale, and installation within Arkansas

Imposes civil penalties up to $5,000 per violation on state entities that enforce federal diesel regulations on exempt engines, with a minimum 12-month suspension of emissions enforcement authority for violating agencies

Mandates termination and a 5-year ban from public office or state employment for individual state employees who violate the act