D.C. Court of Appeals Rules that Cell-Site Simulators Constitute a Search

Privacy Fourth Amendment State Courts

Prince Jones v. United States, No. 15-CF-322 (D.C. Sept. 21, 2017).

On September 21, 2017, the District of Columbia Court of Appeals reversed the judgment of the Superior Court of the District of Columbia, finding that the appellant had been victim to an unlawful search that violated the Fourth Amendment.

The Court of Appeals held that using a cell-site simulator, or “stingray,” to track a suspect via her phone constitutes an invasion of “a reasonable expectation of privacy and [is] thus a search” within the meaning of the Fourth Amendment. The government argued that there can be no reasonable expectation of location privacy while carrying a cell phone.  A cell phone “must continuously broadcast a signal,” and the government, so it claimed, can track this signal. The Court responded that the Fourth Amendment expectation of privacy test is not based on how likely it is that the government could access information in a given scenario. Rather, this test depends on a normative understanding “consistent with the nation’s traditions and values” that the government should access that information.

This case stems from a police investigation in which officers used a cell-site simulator to locate Jones for alleged sexual assault. A cell-site simulator is a portable device that mimics a cell phone tower and causes nearby cell phones to break connections with their networks. The cell phones then connect to the simulator and identify themselves by phone number and other codes. Using this technology, the officers were able to locate the suspect. The Court explained that activity by the government is a search under the Fourth Amendment if it invades an actual and reasonable expectation of privacy. It reasoned that the simulator is a tool that “actively induces the phone to divulge its identifying information” for which the only countermeasure seems to be turning off one’s phone. Given that most people feel obliged to carry a cell phone, the Court decided that use of a cell-site simulator is a search and requires a warrant to preserve an appropriate level of privacy.

Judge Thompson dissented based on the specific facts of the case. According to Judge Thompson, a suspect who is driving on a public road and in possession of a stolen cell phone does not have a reasonable expectation of privacy with regard to her location. She explains that factors such as tracking apps (like Find my iPhone), cell-site location information, and the efforts by the police to find the stolen phone make it unreasonable for a suspect traveling in public to have an expectation that her location will be private. Judge Thompson would have upheld the conviction of the suspect. However, she notes that in cases where a suspect has a reasonable expectation to privacy, police officers do need to obtain a warrant before employing a cell-site simulator.

Cyrus Farivar on Ars Technica provides a brief overview of the case and discusses similar litigation that has occurred recently around the country. Dave Maas and Adam Schwartz, writing for the Electronic Frontier Foundation, praise the decision and point out that while there has been an effort by police to keep the use of cell-site simulator technology out of the public eye, this decision will make it more difficult for them to do so.


Phillip Takhar is a 2L student at Harvard Law School.