Story highlights Police, homeland security, businesses see growing market for drones domestically

Concerns about safety, operations and privacy if drones proliferate in United States

Congress recognizes anticipated drone market; bill would spell out certain uses

Police drones circling overhead, ready to help search for lost children, rescue stranded boaters and capture criminals.

Or drones equipped with lethal weapons, high-tech cameras able to see through clothing, and technology that monitors a person's visit to religious or political events.

Those were divergent and tricky scenarios discussed at a congressional hearing on Thursday (October 25), as lawmakers contemplated a market that experts believe could grow to 10,000 unmanned aircraft in five years.

Photos: Photos: Military drones Photos: Photos: Military drones Military drones – An Israeli Hermes 500 UAV flies over the Hatzerim air force base near Beersheva, Israel, during an air show at the graduation ceremony of Israeli pilots on June 30, 2011. Hide Caption 1 of 12 Photos: Photos: Military drones Military drones – Israeli soldiers prepare to launch a Skylark drone during a drill on January 16, 2012 near Bat Shlomo, Israel. The Skylark can carry a camera payload of up to 1 kilogram, has an operational ceiling of 15,000 feet, and allows users to monitor any designated point within a 15-kilometer radius. The Skylark unit consists of a ground control element and three drones, which provide battalion-level commanders with real-time information. Hide Caption 2 of 12 Photos: Photos: Military drones Military drones – An Israel Aerospace Industries UAV on display at the Singapore Airshow on February 15. Hide Caption 3 of 12 Photos: Photos: Military drones Military drones – A U.S. Air Force MQ-1 Predator UAV assigned to the California Air National Guard's 163rd Reconnaissance Wing flies near the Southern California Logistics Airport in Victorville, California, on January 7, 2012. Hide Caption 4 of 12 Photos: Photos: Military drones Military drones – A model of of the European "Neuron" UAV at the Paris Air Show in Le Bourget, France in 2005. The UAV is an European Research project led by Dassault Aviation. Hide Caption 5 of 12 Photos: Photos: Military drones Military drones – An MQ-9 Reaper unmanned aircraft vehicle (UAV) sits in a shelter at Joint Base Balad, Iraq, after a mission on November 10, 2008. According to the U.S. Department of Defense, the Reaper can carry up to 3,750 pounds of laser-guided bombs and missiles. Hide Caption 6 of 12 Photos: Photos: Military drones Military drones – A British MQ-9 Reaper sits on a runway on March 17. Both British and American Reapers are deployed to Afghanistan. Hide Caption 7 of 12 Photos: Photos: Military drones Military drones – U.S. Marines perform operational checks on a Marine Squadron Two (VMU-2) UAV before a launch at Speed Bag Airfield, near Niland, California, on October 25, 2011. Hide Caption 8 of 12 Photos: Photos: Military drones Military drones – An Iranian-made drone is displayed during the Army Day celebrations in Tehran on April 18, 2010. Hide Caption 9 of 12 Photos: Photos: Military drones Military drones – A model of a surveillance drone built by Dassault Aviation and BAE Systems is displayed at the International Paris Air show in 2011. Hide Caption 10 of 12 Photos: Photos: Military drones Military drones – Chinese visitors examine an unmanned helicopter drone at the China Aviation Expo in Beijing on September 21, 2011. Hide Caption 11 of 12 Photos: Photos: Military drones Military drones – A model of China's "Dark Sword" UAV. According to Jane's Defense & Security Intelligence & Analysis, the drone remains only a model, but offers an example of where China may go with its drone technology. Hide Caption 12 of 12

Congress has ordered the Federal Aviation Administration t o develop plans to integrate them into the national airspace system used by jetliners, private and military planes, helicopters and blimps by 2015.

But there are challenges with safety and operations with anticipated police, homeland security, private and commercial use. Privacy, another concern, was looked at closely at the congressional field hearing in Texas.

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"We need to establish clear guidelines about when and for what purpose law enforcement agencies, private citizens, and businesses can use drones," said Rep. Ted Poe, a Texas Republican and chairman of the House Judiciary subcommittee on crime, terrorism, and homeland security.

In many respects, privacy issues involving drones are no different than those presented by other aircraft and satellites, experts said. But traditional aircraft are costly and expensive to maintain, placing natural limits on their use.

The low cost of drones will "erode that natural limit," allowing governments to conduct regular surveillance on people, said Chris Calabrese, legislative counsel for the American Civil Liberties Union.

"As the number of drones rises, so, too, will the number of suspects," said Rep. Hank Johnson, a Georgia Democrat. "During the civil rights movement, would activists have left their homes if they knew" they were being monitored from cameras 30,000 feet above?" he asked.

"If we take a Laissez-faire attitude towards this, we will see an erosion of our liberties," Johnson said.

Experts testified that Supreme Court case law regarding police aerial surveillance relies heavily on the concept of the public's "reasonable expectation" of privacy.

But those expectations will change as drones become more commonplace, said David Leebron, president of Rice University and former Dean of Columbia Law School.

"As technology changes, if we take no action, so do our expectations," Leebron said.

So several witnesses at the hearing said a legislative fix is needed to uphold current standards of privacy.

A bill introduced by Poe would prohibit the FAA from issuing a drone permit for use by law enforcement unless it is related to a warrant for the investigation of a felony, with some exceptions. It also would prohibit individuals from conducting surveillance on private individuals or private property without the owner's consent.

"We must decide now when drones can and cannot be used in order to ensure constitutional safeguards," Poe said. "Technology may change with time, but the Constitution does not."

But others cautioned against action that could stifle industry.

"I think we're at the birth of this technology," said David Crump, a professor at the Houston University Law Center. "It's true that it's exploding; it's a very fast growing baby," he said, "But we wouldn't want to tell Alexander Graham Bell at the birth of the telephone" to stop development because of privacy concerns.