Following the historic Lindbergh kidnapping (the abduction and murder of Charles Lindbergh's toddler son), United States Congress adopted a federal kidnapping statute—popularly known as the Lindbergh Law — which was intended to let federal authorities step in and pursue kidnappers once they had crossed a state border with their victim.
The theory behind the Lindbergh Law was that federal law enforcement intervention was needed because state and local law enforcement officers could not effectively pursue kidnappers across state borders; since federal law enforcement officers, such as FBI agents, have national enforcement authority, Congress believed they could do a much more effective job of dealing with kidnappings than could state and local authorities.