Drones are well-known for their ability to hunt down suspected terrorists abroad, but they have also increasingly become a popular tool of police departments around the country.
Drones are cheaper to build and fly than helicopters, making them a cost-effective option for police departments looking to gain a bird's eye view of a scene. But privacy groups are sounding alarm that there aren't enough legal safeguards in place to prevent drones from being used for mass surveillance.
The privacy groups are pushing Congress to pass a law that would set nationwide restrictions on how police can use drones.
Some of the biggest police departments that have received authorization from the FAA to fly drones include Houston, Seattle, Miami-Dade and Arlington, Texas. Alameda County, Calif. is also looking into buying the devices.
Aviel Sanchez, a lieutenant with the Miami-Dade Police Department, said his department received FAA authorization in July 2011 but has yet to fly a drone in a mission.
"It's nice to have that capability. If it does... provide a service while safeguarding our property, our personnel and the citizens, then by all means, we'll use that," he said.
Smaller departments, such as Mesa County, Colo.; Ogden, Utah; and North Little Rock, Ark. are also using the technology, according to the drone trade group.
But the FAA has instituted strict limits on the agencies that have received authorization so far.
The FAA's standard authorization requires drones to be flown only during the day, below 400 feet and within the line of sight of the drone operator. Sanchez said Miami-Dade's drones are limited to 300 feet above the ground and are not allowed to fly over populated areas or near downtown high-rises.
But those restrictions are about preventing collisions and keeping the skies safe—not protecting privacy.
"Drones should only be used if subject to a powerful framework that regulates their use in order to avoid abuse and invasions of privacy," Chris Calabrese, a legislative counsel for the American Civil Liberties Union, said during a congressional forum in Texas last month.
He argued police should only fly drones over private property if they have a warrant, information collected with drones should be promptly destroyed when it's no longer needed and domestic drones should not carry any weapons.
He argued that drones pose a more serious threat to privacy than helicopters because they are cheaper to use and can hover in the sky for longer periods of time.
A congressional report earlier this year predicted that drones could soon be equipped with technologies to identify faces or track people based on their height, age, gender and skin color.
Lawmakers have introduced several bills this session to limit police use of drones.
Rep. Austin Scott (R-Ga.) and Sen. Rand PaulRand PaulRand Paul rejects label of 'Trump's most loyal stooge' GOP healthcare plans push health savings account expansion Congress must reform civil asset forfeiture laws MORE (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 PoeTed PoeA guide to the committees: House Lawmakers debate allowing cameras in courtrooms Hey Congress: Where’s the ban on ISIS? MORE's (R-Texas) Preserving American Privacy Act would only allow police to use drones with a warrant and to investigate a felony.
"Both parties cast a skeptical eye toward drone surveillance in law enforcement," Rep. Hank Johnson (D-Ga.) said at the congressional forum in Texas, which was organized by Poe.
Ben Gielow, general counsel for the Association for Unmanned Vehicle Systems International, argued that many of the concerns about domestic drones involve hypothetical technology that is not in place today.
He explained that drones can be used for important missions like locating a missing child or providing an aerial view for a SWAT team raiding a house.
He said existing constitutional protections and privacy laws are sufficient safeguards against abuse and that drone-specific legislation is unnecessary.
"Over the last 225 years, the court system has done a pretty good job of protecting our Fourth Amendment rights, and that is something we absolutely support," he said.