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

HB 3515 prohibits Missouri state and local governments from using taxpayer funds to enforce federal emissions regulations on diesel-powered commercial vehicles, including trucks, buses, and transporters. It directly affects state agencies, local officials, and businesses operating these vehicles by banning enforcement actions like inspections or fines related to emissions control devices. The law imposes $100,000 civil penalties on entities employing officials who knowingly enforce such federal rules, and allows lawsuits to recover attorney fees and costs. Violators must pay court costs if sued, with no immunity for government employees acting under federal authority.