What is  Federal Pre-emption?

In some cases, the federal government regulates a particular land use or activity and therefore states, and local jurisdictions are prohibited from regulating the matter themselves. In order for federal law to pre-empt state or local regulations, the federal statute must either expressly preempt state regulation in the field, or state law must conflict with the operation or objectives of federal law (California Coastal Commission v. Granite Rock Company, 480 U.S. 572 (1987)). In such cases, local regulations that do not conflict with the objectives of the federal regulations, and do not stand as an obstacle to them, may still be a lawful enforcement of local government police power. An example of such regulation is the federal Telecommunications Act of 1996. While the Act allows local jurisdictions to regulate the location and construction of wireless facilities, it prohibits the local jurisdiction from regulating the placement of the facility on the basis of the environmental effects of radio frequency transmissions (47 U.S.C. § 332(c)(7)).