Cell-site simulators, colloquially referred to as IMSI Catchers or by brand names such as "Stingrays" or "King Fisher" are surveillance tools used by state agencies to identify or track mobile devices (and, of course, the individuals associated with such devices). Compared to other surveillance devices, IMSI Catchers are inherently invasive. They are designed to impersonate cell towers, in both functionality and appearance. As a result, IMSI Catcher surveillance is broad and indiscriminate -each time an IMSI Catcher is deployed against a specific target, it interferes with all devices in range. Each time an IMSI Catcher is used against one specific target, it can interfere with the privacy of thousands, collecting the digital identifiers (IMSI, IMEI) of all mobile devices within range. With these identifiers, otherwise anonymous individuals can be geo-located or tracked. In addition to the privacy interference, IMSI Catchers interfere with the functionality of mobile devices in range, preventing them from sending or receiving phone calls, text messages or data, including emergency 911 calls.
The secrecy surrounding the use of these devices has been significant, with law enforcement agencies in Canada generally refusing to acknowledge, or even deny, whether they have ever made use of such a device. The Vancouver Police (VPD), for example, have refused to respond to a freedom of information demand from the Pivot Legal Society for any records relating to its use of these devices. CIPPIC and Christopher Parsons from Citizen Lab represented an intervener in the appeal of that refusal, OpenMedia. VPD defends its decision on the basis that acknowledging any IMSI Catcher would undermine their utility as surveillance tools. However, as we pointed out in the intervention, a lot of information is already in the public record regarding the capabilities of these devices and their use by state agencies, and there is a compelling public interest in publicizing use of these devices, to facilitate public debate regarding the appropriate parameters of their use. UPDATE: On May 25, 2016, after reviewing the record of the appeal, VPD issued a response, indicating that they do not own an IMSI Catcher and have no records relating to the use of such devices. However, ongoing questions remain regarding whether VPD has used these devices in past investigations through the aegis of the RCMP.