Department of Justice Policy Guidance: Use of Cell-Site Simulator Technology

The following policy guidance was released by the Department of Justice September 3, 2015.

Department of Justice Policy Guidance: Use of Cell-Site Simulator Technology

Page Count: 7 pages
Date: Septmeber 3, 2015
Restriction: None
Originating Organization: Department of Justice
File Type: pdf
File Size: 1,671,172 bytes
File Hash (SHA-256): FA7BBD448DE12D14746EFAE4B0E8E3B6523D4B4BD865470F62C268BCAC97120E

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Cell-site simulator technology provides valuable assistance in support of important public safety objectives. Whether deployed as part of a fugitive apprehension effort, a complex narcotics investigation, or to locate or rescue a kidnapped child, cell-site simulators fulfill critical operational needs.

As with any law enforcement capability, the Department must use cell-site simulators in a manner that is consistent with the requirements and protections of the Constitution, including the Fourth Amendment, and applicable statutory authorities, including the Pen Register Statute. Moreover, any information resulting from the use of cell-site simulators must be handled in a way that is consistent with the array of applicable statutes, regulations, and policies that guide law enforcement in how it may and may not collect, retain, and disclose data.

As technology evolves, the· Department must continue to assess its tools to ensure that practice and applicable policies reflect the Department’s law enforcement and national security missions, as well as the Department’s commitments to accord appropriate respect for individuals’ privacy and civil liberties. This policy provides additional guidance and establishes common principles for the use of cell-site simulators across the Department. The Department’s individual law enforcement components may issue additional specific guidance consistent with this policy.


Cell-site simulators, on occasion, have been the subject of misconception and confusion. To avoid any confusion here, this section provides information about the use of the equipment and defines the capabilities that are the subject of this policy.

Basic Uses

Law enforcement agents can use cell-site simulators to help locate cellular devices whose unique identifiers are already known to law enforcement, or to determine the unique identifiers of an unknown device by collecting limited signaling information from devices in the simulator user’s vicinity. This technology is. one tool among many traditional law enforcement techniques, and is deployed only in the fraction of cases in which the capability is best suited to achieve specific public safety objectives.

How They Function

Cell-site simulators, as governed by this policy, function by transmitting as a cell tower. In response to the signals emitted by the simulator, cellular devices in the proximity of the device identify the simulator as the most attractive cell tower in the area and thus transmit signals to the simulator that identify the device in the same way that they would with a networked tower. A cell-site simulator receives and uses an industry standard unique identifying number assigned by a device manufacturer or cellular network provider. When used to locate a known cellular device, a cell-site simulator initially receives the unique identifying number from multiple devices in the vicinity of the simulator. Once the cell-site simulator identifies the specific cellular device for which it is looking, it will obtain the signaling information relating only to that particular phone. When used to identify an unknown device, the cell-site simulator obtains signaling information from non-target devices in the target’s vicinity for the limited purpose of distinguishing the target device.

What They Do and Do Not Obtain

By transmitting as a cell tower, cell-site simulators acquire the identifying information from cellular devices. This identifying information is limited, however. Cell-site simulators provide only the relative signal strength and general direction of a subject cellular telephone; they do not function as a GPS locator, as they do not obtain or download any location information from the device or its applications. Moreover, cell-site simulators used by the Department must be configured as pen registers, and may not be used to collect the contents of any communication, in accordance with 18 U.S.C. § 3127(3). This includes any data contained on the phone itself: the simulator does not remotely capture emails, texts, contact lists, images or any other data from the phone. In addition, Department cell-site simulators do not provide subscriber account information (for example, an account holder’s name, address, or telephone number).


When making any application to a court, the Department’s lawyers and law enforcement officers must, as always, disclose appropriately and accurately the underlying purpose and activities for which an order or authorization is sought. Law enforcement agents must consult with prosecutors in advance of using a cell-site simulator, and applications for the use of a cell-site simulator must include sufficient information to ensure that the courts are aware that the technology may be used.

1. Regardless of the legal authority relied upon, at the time of making an application for use of a cell-site simulator, the application or supporting affidavit should describe in general terms the technique to be employed. The description should indicate that investigators plan to send signals to the cellular phone that will cause it, and non-target phones on the same provider network in close physical proximity, to emit unique identifiers, which will be obtained by the technology, and that investigators will use the information collected to determine information pertaining to the physical location of the target cellular device or to determine the currently unknown identifiers of the target device. If investigators will use the equipment to determine unique identifiers at multiple locations and/or multiple times at the same location, the application should indicate this also.

2. An application or supporting affidavit should inform the court that the target cellular device (e.g., cell phone) and other cellular devices in the area might experience a temporary disruption of service from the service provider. The application may also note, if accurate, that any potential service disruption to non-target devices would be temporary and all operations will be conducted to ensure the minimal amount of interference to non-target devices.

3. An application for the use of a cell-site simulator should inform the court about how law enforcement intends to address deletion of data not associated with the target phone. The application should also indicate that law enforcement will make no affirmative investigative use of any non-target data absent further order of the court, except to identify and distinguish the target device from other devices.

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