Federal Premption of State/Local RFI Regulations
At times, local and state governments have tried to restrict Amateur Radio operations by imposing ordinances aimed at controlling radio frequency interference – RFI. Under these ordinances and statutes, local governments have tried to “shut down” amateur radio operations on the basis that the RFI is a nuisance to the affected neighbor/s.
In 1982 Congress passed P.L. 97-259, which gives exclusive jurisdiction to regulate RFI to the FCC, preempting state and local ordinances that attempted to do so.
For a better understanding of the federal preemption policy, you will want to read several online articles available: