In my piece the other day covering courtroom revelations about the FBI's use of cellphone-tracking technology, often generically referred to as "stingray" after one manufacturer's product, I mentioned the Los Angeles Police Department's use of the same tools. Soon after, I received an official LAPD fact sheet that was prepared in response to an LA Weekly article I referenced in an earlier piece. The fact sheet helpfully clarifies not only the details of the LAPD's policy regarding cellphone tracking, but also the capabilities of the same. But I'm not sure that it necessarily settles concerns about how forthright the LAPD is being about the tracking technology it uses, since the department admits it's describing the technology to judges in a way that federal agents have been told is inadequate.
Stingray-type devices essentially emulate cellphone towers, pinging mobile devices within their range and thereby locating those devices. The LAPD fact sheet emphasizes that the location-finding ability of the technology is imprecise — this is why the FBI in the Rigmaiden case started with a stingray device, and then went to a shorter-range, hand-held device to find Rigmaiden.
Any electronic monitoring equipment/techniques utilized by the LAPD can only gather data regarding the cellular phones in the area of a particular cell tower and from a particular carrier at any one time. This data only identifies the cellular phone by its carrier (i.e. Sprint, Metro PCS, Verizon) and gives no information regarding the subscriber's identity or their location.
The fact sheet than goes on to explain something that hasn't been clear before — that cellphones might be pinged, but they can't be identified without the cooperation of a phone company.
In order to identify a particular handset, it is necessary to have the cooperation of the cellular provider, which provides the necessary identifiers. This cooperation will only occur after being served with a signed court order. The cooperation of the cellular provider is governed by the Communications Assistance for Law Enforcement Act (1994), which mandates cellular providers to modify the design of their equipment, facilities and services to allow law enforcement to conduct electronic surveillance.
That may not sound like much of a safeguard, given the deference most people display toward law enforcement and the legal requirements under which telecoms operate. But we recently discovered that many communications companies have been unexpectedly protective of their customers' privacy, or at least surprisingly uncooperative with federal agencies, to the point that both ICE and the FBI are upset. Cricket features in complaints by both agencies, but so do several other companies that resist over-broad requests for information and even ignore queries. So the extra step of having to go through a telecommunications company in order to identify the mobile devices pinged by a stingray does seem to add an extra layer of protection — especially for people who aren't specific targets and don't want their location information vacuumed up as collateral damage.
Less reassuring is confirmation that requests to use stingray technology are submitted to judges for approval under the umbrella of older (and less intrusive) pen register requests.
The use of the term "pen register/trap and trace" is used to describe the technology where by a cellular provider displays the location of a cell tower used by the cell phone that is the subject of court order. The term is related to older technology of landline services but is now used to describe the interaction between cellular towers and the cell phones that operate on them.
The LAPD is probably following the FBI's lead on this, but the federal practice is pissing off judges so thoroughly that some U.S. Attorneys have found it necessary to caution agents to specify the technology they intend to use in their court submissions. If the judicial system finds the term "pen register/trap and trace" insufficient description for federal agents to use in describing what are really a broad range of technologies with various capabilities, the same concerns apply to the LAPD, too.
Full fact sheet here (PDF).