By Megan Haugh


Last weekend, my fiancé purchased a small drone[1] at the nearest Best Buy.  This drone, weighing less than two-hundred and forty-nine grams, fits in the palm of the hand.[2]  With the ability to fly at “a max altitude of 4,000 meters” (about two-and-a-half miles) and capture 4K video, this small drone truly impresses.[3]  Before my fiancé flew this drone though, he registered it with the Federal Aviation Administration (FAA).  He is not alone.  In the United States, 868,804 drones are registered with the FAA.[4]  (372, 157 drones are registered for “commercial use” and 496,647 drones are registered for “recreational use.”)  Recently, the FAA stated “unmanned Aircraft Systems, or drones, are rapidly becoming a part of our everyday lives.  They are quickly increasing in numbers and complexity.”[5]


In Katz v. United States, Justice Harlan set forth the test for a reasonable expectation of privacy—(1) a person must manifest a subjective belief that he had privacy and (2) society must find the person’s belief is objectionably reasonable.[6]  I (probably like most people) thought I had a reasonable expectation of privacy on my property.  But as drones, like the model my fiancé purchased, become increasingly common, my expectation of privacy seems less reasonable under the second prong of Justice Harlan’s test.  In fact, (according to two Supreme Court decisions) my expectation of privacy has not been reasonable for a while.  In California v. Ciraolo, police officers flew over the defendant’s backyard (at an altitude of approximately 1,000 feet) and discovered marijuana.[7]  In that case, the Supreme Court did not find a violation of the defendant’s Fourth Amendment right.[8]  The Court stated, “The Fourth Amendment simply does not require the police traveling in the public airways at this altitude to obtain a warrant in order to observe what is visible to the naked eye.”[9]  Similarly, in Florida v. Riley, police officers flew a helicopter over the defendant’s greenhouse (at an altitude of approximately 400 feet) and discovered—through two open roof panels—marijuana.[10]  In that case, the Supreme Court, again, did not find a violation of the defendant’s Fourth Amendment right.[11]  Under Justice Harlan’s reasonable expectation of privacy test, the defendant passed the first prong and failed the second prong.[12]


Will the Supreme Court’s rulings in California v. Ciraolo and Florida v. Riley extend to drones used by law enforcement?  I think so.  Like a helicopter or private plane, a drone can fly in public airspace and fly at the same altitudes.  One of the biggest differences is that, unlike a helicopter or plane, a police officer does not “observe what is visible to the naked eye” with a drone.  Rather a police officer observes what is visible to a camera.  In light of the facts in Florida v. Riley, this distinction seems irrelevant.  Because a police officer observed marijuana—through two open roof panels—at a height of 400 feet, it’s hard to believe that they observed marijuana with the “naked eye.”  Under California v. Ciraolo and Florida v. Riley, I think warrantless drone use by law enforcement is permissible.


[1] See DJI Mini 2 Fly More Combo Quadcopter with Remote Controller, Best Buy (

[2] Id.

[3] Id.

[4] UAS by the Numbers, Federal Aviation Administration (Mar. 22, 2021 2:32 PM) (

[5] Id.

[6] See Katz v. United States, 389 U.S. 347 (1967).

[7] See California v. Ciraolo, 476 U.S. 207 (1986).

[8] Id.

[9] Id.

[10] See Florida v. Riley, 488 U.S. 445 (1989).

[11] Id.

[12] Id.

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