What would be meaningful is if the FBI were to explain under what circumstances the FBI believes that the use of drones violates the Fourth Amendment. Sen. Paul reached the same conclusion, quickly firing off a follow-up letter stating that "it is important that you clarify your interpretation of when an individual is assumed to have a reasonable expectation of privacy."
Under what circumstances does the FBI believe the use of a drone could violate a reasonable expectation of privacy? Does it matter whether the drone is flying over a public street or over private property? Does it matter whether the drone is being used to engage in surveillance of a constitutionally protected space such as the inside of a house? What if the drone is using sensory-enhancing technology such as thermal imaging? Does the Fourth Amendment prohibit the FBI from engaging in thermal imaging of a house without a warrant?
Source: ACLU. Read full article. (link)