Recently, California passed legislation banning the use of warrantless drones by police for surveillance purposes. The only exception to this legislation is in “exigent circumstances” as reported by Reason Magazine. The bill passed 25 to 8. The bill requires that police obtain a warrant which is based on probable cause before they can use a drone for surveillance purposes.
When the Assembly passed the bill, some astute Reason commenters wondered if police do not have to obtain a warrant for helicopter surveillance, why should they be required to get one for drone surveillance? In the 1989 case Florida v. Riley, the U.S. Supreme Court ruled that since airplanes and helicopters often fly over private property that citizens do not have a reasonable expectation of privacy that their activities will not be observed from the air. Consequently, the police were permitted use evidence obtained without a search warrant from helicopter observation of a greenhouse in which they suspected marijuana was being grown.
The Los Angeles Times also reported on this. According to the Times, a need for greater protection of fourth amendment rights has been generated by the expanded use of drones for surveillance purposes, says Representative Jeff Gorell.
Essentially, this California legislation assures citizens that they have a reasonable expectation of privacy and are free from warrantless surveillance by police by means of a drone.