Domestic drones are now uncommon, but the FAA has predicted that within 20 years, 30,000 commercial and government drones could be flying in U.S. skies.
"Drone technology is largely a product of our war efforts abroad, but the federal government is repurposing these machines for surveillance purposes at home," the ACLU wrote in a blog post announcing the document requests. "As drone technology continues to become cheaper and more powerful, drones are poised to become part of everyday American life."
The ACLU requested information on how the drones are being funded, their technical capabilities, the types of data they are collecting and who has access to the drones and their data. The group asked for information on all of the policies and procedures governing the use of the technology.
The Freedom of Information Act requires federal agencies to release documents to the public, but the law includes exemptions for national security secrets, information that would harm law enforcement investigations and other reasons.
The ACLU issued a report last year calling for restrictions on the use of drones to protect privacy.
The Congressional Research Service examined the legal issues surrounding domestic drone use in a September report. The agency wrote that it is unclear how the courts will apply constitutional privacy protections to drone use, but that Congress could enact laws to restrict the technology.
Lawmakers have introduced several bills this session to limit how police can use drones to gather information.
Rep. Austin Scott (R-Ga.) and Sen. Rand Paul (R-Ky.) introduced the Preserving Freedom from Unwarranted Surveillance Act to require that police obtain a warrant in most circumstances before using drones. Paul's version of the bill explicitly says evidence gathered without a warrant cannot be used in trial.
Rep. Ted Poe's (R-Texas) Preserving American Privacy Act would only allow police to use drones with a warrant and to investigate a felony.
Rep. Shelley Moore Capito (R-W.Va.) introduced the Farmers Privacy Act to restrict the Environmental Protection Agency's ability to use drones to investigate environmental violations. Sen. Barbara Boxer (D-Calif.) filed an amendment to the 2012 farm bill that would have limited the EPA to using drones only if it is more cost-effective than ground inspections, but the amendment was not adopted.