DC: Using Stingray to track a cell phone is a 4A search because it extracts cell phone numbers from phones

The use of a Stingray device by the police to track a cell phone is a search governed by the Fourth Amendment. Stingrays “[f]orce the person’s cellphone to identify itself and reveal its exact location. It is in this sense that a cell-site simulator is a locating, not merely a tracking, device: A cell-site simulator allows police officers who possess a person’s telephone number to discover that person‘s precise location remotely and at will.” Jones v. United States, 15-CF-322 (D.C. Sept. 21, 2017):

Another consequence of cellphones’ “pervasiveness” is that a cell-site simulator can be used by the government not merely to track a person but to locate him or her. See State v. Andrews, 134 A.3d 324, 348 (Md. Ct. Spec. App. 2016). Police have always had the capacity to visually track a suspect from some starting location, and electronic tracking devices like those used in United States v. Knotts, 460 U.S. 276 (1983), and Karo, 468 U.S. 705, have augmented this preexisting capacity. But although the kind of device used in Knotts and Karo is probably more reliable than a human tracker—less prone to discovery than a human and harder to elude—at their core these devices merely enable police officers to accomplish the same task that they could have accomplished through “[v]isual surveillance from public places.? Knotts, 460 U.S. at 282; see also Karo, 468 U.S. at 713. This is because the tracking device must be physically installed on some object that the target will later acquire or use. See, e.g., (Antoine) Jones, 565 U.S. at 402–03 (GPS tracker placed on the defendant‘s wife‘s car); Karo, 468 U.S. at 708 (tracker placed in container of chemicals the defendant had purchased); Knotts, 460 U.S. at 276 (same). These devices do not enable police to locate a person whose whereabouts were previously completely unknown. With a cell-site simulator, however, police no longer need to track a person which they use to force the person’s cellphone to identify itself and reveal its exact location. It is in this sense that a cell-site simulator is a locating, not merely a tracking, device: A cell-site simulator allows police officers who possess a person‘s telephone number to discover that person‘s precise location remotely and at will.

A final consideration is that when the police use a cell-site simulator to locate a person‘s cellphone, the simulator does not merely passively listen for transmissions sent by the phone in the ordinary course of the phone‘s operation. They then proceed to that area with a cell-site simulator, which they use to force the person’s cellphone to identify itself and reveal its exact location. It is in this sense that a cell-site simulator is a locating, not merely a tracking, device: A cell-site simulator allows police officers who possess a person‘s telephone number to discover that person‘s precise location remotely and at will.

Instead, the cell-site simulator exploits a security vulnerability in the phone—the fact that cellphones are, in the words of the defense expert, “dumb devices,” unable to differentiate between a legitimate cellular tower and a cell-site simulator masquerading as one—and actively induces the phone to divulge its identifying information. Once the phone is identified, it can be located. So far as the present record reveals, the only countermeasure that a person can undertake is to turn off his or her cellphone or its radios (put it in―airplane mode ), thus forgoing its use as a communication device.

The preceding considerations lead us to conclude that the use of a cell-site simulator to locate Mr. Jones‘s phone invaded a reasonable expectation of privacy and was thus a search. …