Definition of Federal preemption
The U.S. Constitution and acts of Congress have given to the federal government exclusive power over certain matterssuch as interstate commerce and sedition to the exclusion of state jurisdiction. Occurs where federal law so occupies the field that state courts are prevented from asserting jurisdiction. State v. McHorse, 85 N.M. 753, 517 P.2d 75, 79. See also Preemption.
That's the definition of Federal pre emption in Black's Law Dictionary 6th Edition. Courtesy of Cekhukum.com.