Recently obtained government documents reveal that drones have been customized to spy on American citizens including having the ability to intercept and record cell phone calls.

The drones will also be customized to enable “identifying a standing human being at night as likely armed or not.” The document was obtained through a Freedom of Information Act request.

Drones have now been used domestically against an American citizen. Rodney Brossart of Lakota, North Dakota, was arrested after refusing to return six of his neighbor’s cows that crossed onto Brossart’s property. A drone was used to search for the cows and to identify if Brossart was armed.

Critics say domestic drone use could allow police to search property without a warrant. They could identify people who may be stocking up on supplies like food and water.

“That drone is not just picking up information on what’s happening at that specific scene, it’s picking up everything else that’s going on,” Brookings Institution senior fellow Peter Singer said. “Basically it’s recording footage from a lot of different people that it didn’t have their approval to record footage.”