Law enforcement agencies' efforts to conceal the kinds of mass surveillance tools available to them are anti-democratic and will draw a public backlash, an ACLU attorney argued in an essay this week.

The piece by ACLU staff attorney Catherine Crump argues that law enforcement policies at all levels, from the NSA to your local police department, are guided less by the moral calculus than by technical capability. If an act of surveillance or interdiction can be done, the rationale to do so tends to be developed later, she argues.

"The limits of law enforcement surveillance are being determined by what is technologically possible, not what is wise or even lawful," she said Friday in a paper published at "And it’s not uncommon for the police to use a new technology in secret for as long as they can, and then allow the courts to sort out legality once the issue finally comes before them."

Crump points toward automatic license plate readers, surveillance cameras mounted on unmanned drones, and the location history of your cell phone as examples of technology outstripping legal and ethical considerations.

Crump's essay comes on the heels of last week’s conference of the International Association of Chiefs of Police, from which a significant public debate about the limits of technology in public safety has emerged. Georgia Bureau of Investigation Director Vernon Keenan noted that leaks of intelligence gathering methods by Edward Snowden, including about monitoring of U.S. phone records, threaten to erode existing authority to use high-tech equipment.

"The scrutiny that the NSA has come under filters down to us," Keenan said.

However, Philadelphia Police Chief Charles Ramsey also argued that police have to be willing to refrain from the use of some methods for surveillance, even though the methods are possible.