FBI Director Robert Mueller says the US law enforcement agency uses drones for surveillance but does so rarely.
In an appearance before the Senate Judiciary Committee, Mueller says the bureau is developing guidelines for drones and that the privacy implications of using drones are, in Mueller's words, worthy of debate and legislation down the road.
The aerospace industry forecasts a worldwide deployment of almost 30,000 drones by 2018, with the United States accounting for half of them.
