Drones were the hot Christmas gift last year, but where are they now?

"There are still considerable legal, technological and public perception problems to overcome, said Ryan Calo, a robotics law expert from the University of Washington School of Law.

The drone industry is trying to fight heavy local restrictions, fearing state regulations that vary greatly.

"It's amazing that people are being required to register a toy," Calo said. "All toys are potentially dangerous. You could hit someone in the head with a chessboard.""