Increasing use of aircraft in surveillance raises privacy concerns at Senate hearing . Their use would require new definition of unreasonable search , Sen. Grassley says . Drone industry expert says the FAA has strict rules about using the aircraft . `` But what can be done illegally , and how can the government prevent that from happening ? '' Aircraft also used for tracking crops , livestock and farm equipment in U.S .
Increasing use of aircraft in surveillance raises privacy concerns at Senate hearing . Their use would require new definition of unreasonable search , Sen. Grassley says . Drone industry expert says the FAA has strict rules about using the aircraft . Aircraft also used for tracking crops , livestock and farm equipment in U.S .