Earlier this summer, a Connecticut man rigged a handgun to the top of an unmanned aircraft, posting a video of the device hovering in the woods and firing shots. The spectacle raised more concern about how consumers or law enforcement could wreak havoc with drones, a fast-growing technology with immense potential. The leading drone industry group, Federal Aviation Administration (FAA) and some law enforcement groups have spoken out against equipping the unmanned devices with weapons. But as those stakeholders cannot make laws, individuals and police can make a case for arming drones in most of the United States. The prospect of police shooting rubber bullets or spraying tear gas from a drone is slim in the immediate future. But as more UAVs take flight in the U.S., some lawmakers are pushing for clearer restrictions on arming them, in order to reduce fears of users abusing the legal uncertainty. Read MoreDo we need to put drones on a tighter leash?

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Drones could add $82 billion and 100,000 jobs to the U.S. economy by 2025, according to industry group Association for Unmanned Vehicle Systems International. Despite the imminent spread of the aircraft, lawmakers have been slow to address concerns about using them violently. "It's something that could be easily abused in the wrong hands. But technologically, we're not quite there yet," said David Swindell, director of the Center for Urban Innovation at Arizona State University and a drone policy expert.

The FAA—which has primary regulatory authority over drones—says pilots cannot "allow any object to be dropped from an aircraft in flight that creates a hazard to person or property." However, the agency does not ban it if "reasonable precautions" are taken to avoid injuries or property damage.

'Non lethal' vs lethal

At least five U.S. states—Virginia, Wisconsin, Oregon, Nevada and North Dakota—have passed laws barring police from arming drones in some capacity. While lawmakers in North Dakota banned law enforcement from using lethal weapons earlier this year, they scratched "non-lethal" weapons from the final law, leaving the door open for equipment like Tasers and rubber bullets, which can still cause serious harm.

While that state's law has created a stir in recent weeks, theoretically police—or anyone—could make a case that adding "non-lethal" weapons to drones is legal anywhere it hasn't been explicitly forbidden. "Where the law is silent, some police departments may feel they have a license to attach weapons," said Jay Stanley, a senior policy analyst with the American Civil Liberties Union's speech, privacy and technology project.

Oregon passed legislation in 2013 prohibiting law enforcement from arming drones. The state legislator who sponsored the bill is now considering extending the weapons ban to consumers, state government agencies and local governments.

"The landscape has changed. There are tens of thousands more drones flying than a few years ago," said John Huffman, a Republican representative who represents Oregon's 59th District. Huffman and a lawmaker in Nevada stressed that they talked to police in their states while drafting legislation, and they did not seem intent on arming UAVs. The ACLU's Stanley noted that "there's a very strong consensus in the drone community that weaponizing domestic drones is beyond the pale."

But in attempting to grow the industry in their states, drone proponents wanted to take weapons out of the picture to reduce concerns. "I thought it would be good to make it clear these are not military UAVs and these have a lot of really good uses," said Elliot Anderson, a Democratic assemblyman from Nevada's 15th District, who sponsored the bill that banned adding weapons to drones.