For the second night in a row, drones were spotted flying over Paris’s landmarks. Night flights are prohibited in Paris, and the person(s) conducting the illegal flights are still unknown. It has been less than a month since a drone crash-landed on the White House lawn, and Washington, Paris, and all other major cities are still figuring out how to adjust to the new normal, where personal drones are commonplace.

The FAA estimates that by 2018 there may be as many as 7,500 commercial drones in the United States, but this figure excludes drones belonging to hobbyists. And that’s not a small market; 3D Robotics, a hobbyist drone company based in California, says it sells over 100 drone kits per week.

Parrot, a drone company based in Paris, has seen its drone revenue surge as the unmanned aerial vehicles catch on with consumers. The company’s drone revenue in the third quarter of 2014 was 27.7 million euros ($31.5 million), compared with 12.1 million euros in the same quarter of the previous year. Retail (hobbyist) drone sales made up 87.4 percent of their total drone revenue in the third quarter of 2014; the rest came from commercial drones. Parrot estimates that over 700,000 retail drones were sold worldwide in 2014.

How will governments regulate all these drones flying around? We’re starting to get clues.

Drone flights in the United States could be checked by a proposed FAA rule that would, among other changes, require drone operators to keep their drones in their line of sight (no binoculars allowed). This proposed rule would apply only to non-recreational flights, but as hobbyist drone use grows, commercial regulations may be used as a model for future restrictions.

Requiring operators to keep drones in sight would allow law enforcement to charge operators, if they can find them. The Paris drones are flying illegally, but it is difficult to trace a drone on the move back to its controller. In the future, the FAA might require companies to modify their products so the drones can’t be flown in violation of regulations.

A company could hypothetically track the location of both controller and drone and then override the user’s inputs to send the drone back if it was trying to fly out of an estimated line-of-sight radius. DJI, the company that manufactures the drone that crashed at the White House, voluntarily modified its software to set up a blackout zone around the White House. Get too close, and the drone will descend until the user either turns it around or is forced to land it.

If Paris sought similar safeguards, the city would quickly become inhospitable to drone users. Throwing up a no-fly zone around the Place de la Concorde, one of the locations the mystery drone has been visiting, would require a blackout zone larger than the city itself, if manufacturers used the 15.5 mile radius set around the White House. Even a more modest cordon of 5 miles (the no-fly zone surrounding U.S. airports) would be nearly double the size of the city.

Even if cities banned all flights rather than face the risk of a prohibited one, these conservative strategies would be of limited use. Although drones from major manufacturers might be obedient to the law when they come out of the box, hobbyists might be able to jailbreak software or physically modify their machines to get around restrictions.

For do-it-yourself drone operators, the restrictions would never come into play. Voxel8’s 3D printer for electronics could print an entire drone, including the circuit boards, to a user’s specifications. Jasper van Loenen’s Drone It Yourself kit allows a user to clamp rotors to any sufficiently light object and let them bear it aloft. In his demonstration video, he flies a bicycle wheel and a computer keyboard.

While Paris works on finding this week’s drone operators, all cities will need to figure out how to coexist with tomorrow’s.