Preemption Determination Law and Legal Definition

According to 49 CFR 105.5 [Title 49. Transportation Subtitle B Other Regulations Relating To Transportation Chapter I Pipeline And Hazardous Materials Safety Administration, Department Of Transportation Subchapter A Hazardous Materials And Oil Transportation Part 105 Hazardous Materials Program Definitions And General Procedures Subpart A Definitions] Preemption determination means “an administrative decision by the Associate Administrator that Federal hazardous materials law does or does not void a specific State, political subdivision, or Indian tribe requirement.”

Preemption is the rule of law that if the federal government through Congress has enacted legislation on a subject matter it shall be controlling over state laws and/or preclude the state from enacting laws on the same subject if Congress has specifically declared it has "occupied the field."