But just what will they be looking for, and what sophisticated devices will they carry? And how deeply will they peer into the life of the average American?
Questions like that already are beginning to concern some members of Congress, which is looking at proposals that would limit the amount of information unrelated to a crime drones could collect. One bill from Rep. Edward Markey, D-Mass., would require private drone operators to inform the government of any data collected by drones and would require law enforcement to "minimize" the collection of "information and data unrelated to the investigation of a crime."
The draft bill says there "is the potential for unmanned aircraft system technology to enable invasive and pervasive surveillance without adequate privacy protections."
U.S. News & World Report says some analysts estimate "there may be as many as 30,000 unmanned drones operated in the United States by 2020 for uses such as wildfire containment and surveillance, law enforcement and surveying."
But the U.S. Supreme Court in the last decade has tended to keep intrusive police surveillance narrow.
A North Dakota judge, at least for now, has approved what appears to be the first time a drone has been used in the arrest of a U.S. citizen.
U.S. News reported court documents show District Judge Joel Medd rejected a motion for dismissal, ruling there "was no improper use of an unmanned aerial vehicle" and the drone "appears to have had no bearing on these charges being contested."
The case involves Rodney Brossart of Lakota, arrested last year after a 16-hour standoff at his rural house. The facts are rather mundane.
Six cows had wandered onto Brossart's farm and he allegedly refused to return them. That led to the standoff with police from Grand Forks, N.D. The U.S. Department of Homeland Security, relying on an agreement with police, offered the besiegers the use of a drone for surveillance.
Police said the drone was used to make sure Brossart and his family were at home and unarmed when police swept in for arrests. With a change of venue to Grand Forks, the trial is ongoing.
Homeland Security already has started a program to get police departments to adopt the use of drones.
An experiment on a hillside 40 miles north of Los Angeles in June 2010 was part of that effort, The (Wichita Falls, Texas) Times Record News reported.
Department officials hid a device that emitted low-grade radiation inside a pack of cigarettes -- imitating a "dirty bomb," a conventional explosive device wrapped in radioactive material.
The small package was spotted by a drone flying over the hills, the radiation registering on a portable controller "that looked like an oversized Game Boy," the newspaper said.
The Times Record News said Homeland Security has awarded grants to at least 13 police departments to buy small drones, but restrictions imposed by the Federal Aviation Administration and the difficulty of using them have kept most of them grounded.
Congress has enacted a law requiring the FAA to ease restrictions on commercial drone use by 2015, the newspaper said.
Last January, the Electronic Frontier Foundation, based in San Francisco, filed suit against the FAA to get at information on drone flights in the United States. The foundation said the FAA, the only agency allowed to authorize domestic drone flights, has not released detailed information on who is authorized to fly drones within U.S. borders.
Last week, Michael Huerta, acting FAA administrator, said new regulations on how to safely fly unmanned aircraft over U.S. homes and protect individual privacy are now being drafted, the Los Angeles Times reported.
The FAA has approved 106 federal, state and local government agencies to fly drones in U.S. airspace.
Huerta said the regulations should be ready by September 2015.
Anne Nicolli of the U.S. Coast Guard Leadership Development Center took on the issue of drones and other robots in a study, "The Robotic Revolution in Military Affairs: Implications for Leaders." The center has detachments in Virginia and California.
Nicolli said "in 2003 the budget for Department of Homeland Security included $4 billion for technology research. ... Protecting the homeland from terrorists, especially at airports, borders, power plants and ports propelled interest in 'sensory bots' and unmanned vehicles.
"Although robots are showing their value in the war on terrorism both at the battlefield and at the home front," she wrote, "they already reveal their worth in responding to natural and man-made disasters. During the Deepwater Horizon oil spill disaster [in the Gulf of Mexico in 2010], at least four Remote Operated Vehicles and 15 robotic submarines were deployed to the wellhead 5,000 feet below the ocean surface. Unmanned Aerial Vehicles searched for survivors after Hurricane Katrina and [after the Sept. 11, 2001, terror attacks] PackBots and TALONS [unmanned vehicles] assisted in search and rescue missions. Robotic boats have already proven their advantage by operating in conditions too dangerous for sailors such as 'sea state six' when waves are 18 feet or higher."
The coming age of drones and other robots seems assured.
But the U.S. Supreme Court has never been shy about defining the limits of government intrusion.
In 2000's Indianapolis vs. Edmond, the high court ruled 6-3 the city's policy of setting up roadblocks to check for unlawful drugs was unconstitutional. The majority opinion, written by Justice Sandra Day O'Connor, said because the program's "primary purpose is indistinguishable from the general interest in crime control, the checkpoints violate the Fourth Amendment." The Fourth Amendment bans unreasonable searches and seizures, or searches and seizures without probable cause or a warrant.
In 2001's Kyllo vs. U.S., however, Scalia and Thomas jumped to the other side.
In Kyllo, a federal government agent used a "thermal imaging device" to scan a triplex in Florence, Ore., without a warrant to determine whether marijuana was being grown.
The scan showed Danny Kyllo's garage was hot compared to the rest of his home and the neighborhood, consistent with the high-intensity lamps typically used for indoor marijuana growing.
The Supreme Court majority opinion, written by Scalia, reversed a federal appeals court, saying when the "government uses a device that is not in general public use, to explore details of a private home that would previously have been unknowable without physical intrusion, the surveillance is a Fourth Amendment 'search,' and is presumptively unreasonable without a warrant."
The high court has been kinder to more low-tech methods of police investigation.
In 2005's Illinois vs. Caballes, the high court ruled 5-3 -- the seriously ill Rehnquist took no part in the case -- that it was constitutional to make a vehicle search when a drug-sniffing dog alerts officers to contraband during a routine traffic stop.
Justice John Paul Stevens, in the majority opinion, said the ruling "is entirely consistent with our recent decision that the use of a thermal-imaging device to detect the growth of marijuana in a home constituted an unlawful search. ... Critical to that decision was the fact that the device was capable of detecting lawful activity -- in that case, intimate details in a home, such as 'at what hour each night the lady of the house takes her daily sauna and bath.' .... The legitimate expectation that information about perfectly lawful activity will remain private is categorically distinguishable from respondent's hopes or expectations concerning the non-detection of contraband in the trunk of his car. A dog sniff conducted during a concededly lawful traffic stop that reveals no information other than the location of a substance that no individual has any right to possess does not violate the Fourth Amendment."
Fellow liberal Justice David Souter led the dissenters.
"I would hold that using the dog for the purposes of determining the presence of marijuana in the car's trunk was a search unauthorized as an incident of the speeding stop and unjustified on any other ground," he said.
Last January, the Supreme Court said unanimously placing a Global Positioning System tracking device on a vehicle is considered a search under the Constitution.
The ruling came in a Washington drug dealer investigation. A U.S. appeals court in the nation's capital said the data obtained by a GPS device was obtained without a warrant as required by the Fourth Amendment and suppressed it.
The appeals court said other evidence obtained without using the GPS device was admissible because the suspect had no "reasonable expectation of privacy" for a vehicle on the public streets.
The Supreme Court agreed with the appeals court.
Again, Scalia wrote for the majority, saying the government's attachment of "the GPS device to the vehicle, and its use of that device to monitor the vehicle's movements, constitutes a search under the Fourth Amendment." Four other justices signed on to Scalia's opinion. Four others agreed with the judgment in concurring opinions, but for different reasons.
The high court also has agreed to review two cases next term involving police use of dogs, on the low-tech end of the scale.
However, the odds appear to be very good that sometime over the next several years the justices will have to move to the high-tech front and deal with the issue of drone surveillance, and the sophisticated sensors unmanned aerial vehicles can carry.