Motor vehicles; creating the Oklahoma Diesel Engine Freedom Act. Emergency.

SB 457, the Oklahoma Diesel Engine Freedom Act, invalidates federal rules requiring diesel exhaust fluid (DEF) in diesel engines used within Oklahoma, declaring such requirements unconstitutional under the 10th Amendment. It prohibits state agencies and officials from enforcing federal DEF mandates and legalizes the sale and use of diesel engines that do not require DEF in the state. The bill imposes fines up to $5,000 per violation for state entities enforcing federal rules and repeals an existing Oklahoma emission control law. It applies only to vehicles operating solely within Oklahoma, not to interstate commerce.