From the Electronic Frontier Foundation:

As we’ve written in the past, drone use in the United States implicates serious privacy and civil liberties concerns. Although drones can be used for neutral, or even for positive purposes, drones are also capable of highly advanced and, in some cases, almost constant surveillance, and they can amass large amounts of data. Even the smallest drones can carry a host of surveillance equipment, from video cameras and thermal imaging to GPS tracking and cellphone eavesdropping tools. They can also be equipped with advanced forms of radar detection, license plate cameras, and facial recognition. And, as recent reporting from PBS and Slate shows, surveillance tools, like the military’s development of gigapixel technology capable of “tracking people and vehicles across an entire city,” are improving rapidly.