Federal law enforcement agents misled judges for years on what type of wiretaps they were carrying out when they requested permission for so-called "pen register" searches, an email obtained by the American Civil Liberties Union (ACLU) reveals.

Instead of collecting data on incoming and outgoing callers (among other general information), as "pen register" searches are intended to do, the ACLU said that agents commonly used a vehicle-mounted technology called the "stingray" that intercepts all nearby communications in order to pinpoint the location of a particular signal. The ACLU argues that these devices in effect resulted in a de facto wiretap, when that was not yet authorized.

A Freedom of Information Act Request (FOIA) filed by the ACLU returned a revealing email about the use of "stingrays" in law enforcement, showing the office of the United States Attorney for the Northern District of California warning agents to be more specific about the type of technology employed in pen register requests.

“As some of you may be aware, our office has been working closely with the magistrate judges in an effort to address their collective concerns regarding whether a pen register is sufficient to authorize the use of law enforcement’s WIT technology (a box that simulates a cell tower and can be placed inside a van to help pinpoint an individual’s location with some specificity) to locate an individual," the email explained. "It has recently come to my attention that many agents are still using WIT technology in the field although the pen register application does not make that explicit."

“While we continue work on a long term fix for this problem, it is important that we are consistent and forthright in our pen register requests to the magistrates," the email concludes.

"In other words, the federal government was routinely using stingray technology in the field, but failing to 'make that explicit' in its applications to the court to engage in electronic surveillance," ACLU staff attorney Linda Lye wrote in an advisory. "When the magistrate judges in the Northern District of California finally found out what was happening, they expressed 'collective concerns,' according to the emails."

The application of such technology was being considered in an Arizona court case, which got underway Thursday. Lye is arguing that the court should suppress evidence obtained from the use of a "stingray" device in a case involving a hacker that police sought for years.

"We hope that the court sends the clear message to the government that it cannot keep judges in the dark," Lye explained on the ACLU's website. "Judges are not rubber stamps – they are constitutional safeguards of our privacy."

The email obtained through the ACLU's FOIA request was presented as evidence in the case (PDF).


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