In June, the first American citizens in history were arrested with the help of an unmanned Predator drone aircraft.

And the incident could be a glimpse into the future of U.S. law enforcement.

The Federal Aviation Administration next month could make it easier for police departments to obtain and use airborne surveillance drones, according to a report (PDF) by the American Civil Liberties Union.

The federal government has held up the domestic use of unmanned aerial vehicles (UAV) out of concern for the safety of U.S. airspace. The use of UAVs have been mostly limited to the U.S.-Mexico border and in war-zones outside the country.

But pressure is going on the FAA to make it easier for law enforcement agencies to gain permission to use UAVs. "Proposed legislation would require the FAA to grant permits more quickly and allow broader use of the technology by 2015," the ACLU report states. "Meanwhile, amid the mounting pressure, the FAA is planning to create a more permissive approval system for commercial UAV operations, which have been severely restricted until now."

There are hundreds of different models of UAVs, from large fixed-wing aircraft to a tiny drone called the Nano Hummingbird (pictured above). The drones employ a wide range of surveillance technology as well, including high-power zoom lenses, infrared and ultraviolet imaging, see-through imaging and video analytics. Some drones are also large enough to be fitted with weapons.

“Our privacy laws are not strong enough to ensure that the new technology will be used responsibly and consistently with democratic values,” warns the ACLU report. “We need a system of rules to ensure that we can enjoy the benefits of this technology without bringing us a large step closer to a ‘surveillance society’ in which our every move is monitored, tracked, recorded and scrutinized by the authorities.”

The U.S. Surpeme Court ruled in the 1980s that the Fourth Amendment did not categorically prohibit warrantless aerial surveillance of private property. But the cost of purchasing, operating and maintaining aircraft prevented law enforcement agencies from deploying them on a large scale.

“Historically, the fact that manned helicopters and airplanes are expensive has imposed a natural limit on aerial surveillance. But the prospect of cheap, flying video surveillance cameras will likely open the floodgates,” said Jay Stanley, the report’s co-author and senior policy analyst with the ACLU’s Speech, Privacy & Technology Project.

To avoid turning the U.S. into a “surveillance society,” the ACLU has called on the FAA and Congress to implement new privacy regulations concerning UAVs.

“The deployment of drone technology domestically could easily lead to police fishing expeditions and invasive, all-encompassing surveillance that would seriously erode the privacy that we have always had as Americans,” said Catherine Crump, the report’s other co-author and staff attorney with the Speech, Privacy & Technology Project.