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Law Enforcement Use of Drones: Do You Have Your Warrant?

By Emmanuel Emukah

The 21st century has brought unprecedented technological advances, which means more complex legal issues. This raises the question of whether the current rules of law need to change to remain relevant. Unmanned aircraft systems — or drones — are a perfect example.

Drone use has become popular, partly because of its affordability and sophistication. It’s no surprise that it is attractive to law enforcement officers.

Photo of a police drone.Drones can be very useful to law enforcement, especially during emer­gencies, and cities across the United States have found creative ways to use drones. However, this use of drones comes with Fourth Amend­ment concerns, especially when it comes to private residences.

Court rulings

The Fourth Amendment to the U.S. Constitution protects residents from unreasonable searches and seizures by the gov­ernment. The U.S. Supreme Court over the years has used two tests to determine whether a search was reasonable under the Fourth Amendment.

The first test is “trespass,” or physical intrusion, reiterated in the 1928 case of Olmstead v. United States. The second test is “privacy,” originating from the 1967 case of Katz v. United States. The courts have used the privacy test more since the Katz ruling.

Aerial surveillance

There are two leading Supreme Court cases on aerial surveil­lance of private residences. In the 1986 case of California v. Ciraolo, a police officer flew a private plane over a private home where the residents were suspected to be growing marijuana in the backyard.

The officers were able to see the marijuana plants with their naked eyes at an altitude of 1,000 feet, enabling them to obtain a search warrant. The court held that there was no requirement for a search warrant in this scenario because “any member of the public flying in this airspace could have seen everything that these officers observed.”

The court further concluded that the resident’s expecta­tion that his garden was protected from such observation was unreasonable and was not an expectation that society was prepared to honor.

The second aerial surveillance case is the 1989 case of Florida v. Riley, involving similar facts. An officer flew a helicopter over Riley’s property twice at 400 feet, enabling the officer to see marijuana with his naked eyes, leading to a warrant being obtained.

The court followed the same conclusion as in Ciraolo, finding that Riley could not reasonably expect that his greenhouse was protected from the public or official observation from a heli­copter flying within the navigable airspace, thus, there was no constitutional violation.

The case for warrants

You may think that a drone is similar to a heli­copter or a plane and, therefore, the rulings dis­cussed above would apply to drones. However, drones are very different from helicopters and planes. Therefore, it is recommended that city officials obtain a warrant before using a drone to look at private property.

One difference is that, although drones are used by the public, flying drones over private residential property is likely not allowed by the public under the current Federal Aviation Administration (FAA) rules, except in limited circumstances.

Secondly, when seeing something via a drone, the user is not seeing it with the naked eye. Officers using a drone would only see the images via a camera, which can be manipulated in dif­ferent ways, such as zooming in more closely. Thus, the drone could enable them to see things that a naked eye ordinarily would not have seen.

There is also the question of how high a drone must be flying to be used in a legal search that complies with the Fourth Amendment. The FAA allows drones to fly lower than other aircrafts. But it’s uncertain how low a drone could fly over a private home without violating the residents’ privacy. There have been no court cases on this, so this is still unsettled law.

Drones are also notorious for veering off course, and can crash onto private property, undoubtedly resulting in a “search” under the original trespass test. Thus, while there is little precedent, if the city is using the drone to obtain evi­dence, a warrant is likely required.

Adopt a policy

Cities that have or are thinking of purchasing a drone should set out policies regarding drone use to avoid Fourth Amend­ment violations and potential liabilities. Having a policy helps guide employee use and creates public trust.

Legislation has been introduced that may create additional requirements for city drone use. The League will provide infor­mation if the bill gets enacted into law.

For more information about drones, see the League of Minnesota Cities information memo, Drones: Municipal Use and Regulation, available at

Emmanuel Emukah is a research assistant with the League of Minnesota Cities. Contact: or (651) 281-1226.