Florida has adopted a new law that limits the ability of the state to use drones for surveillance.
http://www.cnn.com/2013/04/25/us/florida-drone-law/index.html. The law requires judicial approval before state and local law enforcement may use surveillance drones. The law makes exceptions for instances where there is "imminent danger to life or serious damage to property" or where there is "credible intelligence" which indicates "a high risk of terrorist attack." Currently few law enforcement agencies in Florida have drones. The CNN article states that Miami and Orange County each have two.
In terms of the Fourth Amendment it is important to note that states may adopt more privacy protections, by statute or by constitutional provision, than are guaranteed under the U.S. Constitution. Florida has done so by statute in this instance.
At the federal level the U.S. Supreme Court has decided cases involving surveillance by manned aircraft. California v. Ciraolo, 476 U.S. 207 (1986). In that case the police were not required to obtain a warrant before flying over and observing with the naked eye the backyard of the defendant. Using other equipment beyond human eyesight during the overflight to observe the property would entail a different analysis than Ciraolo. Also the Supreme Court has recently placed an extra emphasis on property rights in the Fourth Amendment context. United States v. Jones, 565 U.S. ___; 132 S.Ct. 945; 181 L.Ed.2d 911(2012). The common law property maxim of cuius est solum eius est usque ad coelum et ad inferos implied that a land owner owned all the land beneath and above his property. This legal maxim is now limited to the area above or below the ground that the landowner can occupy or use in connection with the land so overflights are not prohibited in this regard unless they are too low to the ground. United States v. Causby, 328 U.S. 256; 66 S.Ct. 1062; 90 L.Ed. 1206 (1946). So there might be a property rights based Fourth Amendment argument against drones flying too close to the ground without a warrant.
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