They are light. Small. Fly quiet. Not easily spotted against a big sky. They're like model airplanes -- with one significant difference. They carry high resolution cameras that transmit real time video to the operator.
Daytime. Infrared. Night vision. From 400 feet they can reveal whether someone is carrying a shovel or a machine gun.
Unmanned aircraft systems -- like the Raven and the Wasp -- were developed for battlefield use, but drones are making their way to domestic airspace - in large part because they offer "eyes in the sky" at a mere fraction of a helicopter's cost.
"So basically for the cost of a fully equipped squad car, a police force, or a first responder can have the capability in their trunk to get a bird's eye view of any situation where they need it," said Steve Gitlin, AeroVironment.
LA-based Aerovironment, a leading maker of small drones for the military, has developed what it calls "the Qube", a five-and-a-half pound baby helicopter with a thermal camera that can hover for 40 minutes. It's technology that could significantly aid hostage situations, search and rescue, or, for example, a planned raid on a house with armed bad guys inside.
"To have someone in a van at the end of the block monitoring a live feed from a drone over the house that they can't even hear, God, that'd be great intell," said Tom Dart, Cook County Sheriff.
Sheriff Tom Dart sees drones as potential life-savers. His department is now applying to the FAA for air-space permission to use Drones, and he's got money in the budget for their purchase.
Some law enforcement agencies nationwide already have drones though their permitted use is limited.
Its advocates see the drones as a valuable tool in law enforcement's tool box. But who governs how they are used? What are the rules of engagement?
"People have a right to know that government isn't going to be spying on them," said Ed Yohnka, ACLU.
Critics fear that the zeal to use flying cameras will muzzle the discussion of civil liberties -- that drones could be used for warrantless surveillance -- monitoring activity that our constitution protects.
"Do you really want a drone looking in your bedroom window or following your child to school? Once that information is generated, it tends to leak out," said Prof. Lori Andrews, Kent College of Law.
The rules governing their use have yet to be drawn. Critics insist that when they are the process needs to be transparent.
"They ought to have public hearings. They ought to discuss how it's going to be used, and they ought to discuss publicly what the privacy guidelines are," said Yohnka.
"I think the public would be very supportive of this if they knew here's the exact scenarios we're using it for and why. I think they'd be on board," said Dart.
Even before privacy issues, there are airspace questions. You can't have little aircraft flying all over without rules.
The FAA is responsible for setting those guidelines, and is in the process of doing that.
The current rules for the small number of agencies that already have domestic drones require that they fly no higher than 400 feet, and they must be within a mile line-of-sight of the operator. That may very well change.