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Cellular-site data tracking

This morning, the U.S. Supreme Court agreed to hear the case of Carpenter v. United States (16-402).  The issue is whether the warrantless search and seizure of cell phone records that detail the location and movement of the cell phone user over a period of time is permitted by the Fourth Amendment.

In this case, the defendants were charged with nine armed robberies in violation of the Hobbs Act (18 U.S.C. §1951).  At trial, the Government introduced the defendants' cell phone records to show that each defendant used his cell phone within 1 1/2 to 2 miles of several locations during the times the robberies occurred.  The Government obtained these records pursuant to the Stored Communications Act (18 U.S.C. §2703(d)), which permits the Government to require disclosure of certain telecommunication records when "specific and articulable facts show that there are reasonable grounds to believe that the content of a wire or electronic communication, or the records or other information sought, are relevant and material to an ongoing criminal investigation."

The defendants moved to suppress the Government's cell-site evidence arguing that under the Fourth Amendment, seizure of the records required a warrant supported by probable cause.  The District Court denied the motion holding that the cell-site records obtained by the Government did not constitute a search under the Fourth Amendment. The defendants were subsequently convicted.

The defendants maintained the Fourth Amendment argument on appeal.  The Sixth Circuit agreed with the District Court and focused on the distinction between the content of personal communication (which is private) and the information necessary to transport the communication (which is not private).

In the twentieth century, the telephone call joined the letter as a standard form of communication. The law eventually followed, recognizing that police cannot eavesdrop on a phone call--even a phone call placed from a public phone booth--without a warrant. See Katz, 389 U.S. at 352-55. But again the Supreme Court distinguished between a communication's content and the information necessary to send it. In Katz, the Court held that "[t]he Government's activities in electronically listening to and recording the petitioner's words" was a search under the Fourth Amendment. Id. at 353 (emphasis added). But in Smith, the Court held that the police's installation of a pen register--a device that tracked the phone numbers a person dialed from his home phone--was not a search because the caller could not reasonably expect those numbers to remain private. "Although [the caller's] conduct may have been calculated to keep the contents of his conversation private, his conduct was not and could not have been calculated to preserve the privacy of the number he dialed." Smith, 442 U.S. at 743 (emphasis in original).

Today, the same distinction applies to internet communications. The Fourth Amendment protects the content of the modern-day letter, the email. See United States v. Warshak, 631 F.3d 266, 288 (6th Cir. 2010). But courts have not (yet, at least) extended those protections to the internet analogue to envelope markings, namely the metadata used to route internet communications, like sender and recipient addresses on an email, or IP addresses. See, e.g., United States v. Christie, 624 F.3d 558, 574 (3d Cir. 2010); United States v. Perrine, 518 F.3d 1196, 1204-05 (10th Cir. 2008); United States v. Forrester, 512 F.3d 500, 510 (9th Cir. 2007).

The business records here fall on the unprotected side of this line. Those records say nothing about the content of any calls. Instead the records include routing information, which the wireless providers gathered in the ordinary course of business. Carriers necessarily track their customers' phones across different cell-site sectors to connect and maintain their customers' calls. And carriers keep records of these data to find weak spots in their network and to determine whether roaming charges apply, among other purposes. Thus, the cell-site data--like mailing addresses, phone numbers, and IP addresses--are information that facilitate personal communications, rather than part of the content of those communications themselves. The government's collection of business records containing these data therefore is not a search.

Amy Hamm at SCOTUSblog also reported on this case this morning.  It can be found here


As presently phrased, the question presented is broad enough to invite the Court to revisit many aspects of its Fourth Amendment jurisprudence beyond the third party doctrine.


Is there a test for what constitutes a "search" beyond the reasonable-expectation-of-privacy and Jones "trespass" formulations?

Is the Court going to adhere to the principle that warrantless searches are presumptively unreasonable, unless they fall within a (supposedly) narrow exception? Or has the time come to determine the "reasonableness" of any particular search by a case-by-case, totality-of-the-circumstances, balancing, approach? Which formulation is better supported by the text and history of the Fourth Amendment?

By the way, is there really much of a difference between the Stored Communications Act's "reasonable grounds" test and "probable cause"? If not, wouldn't the disclosure order issued by the district court judge, in effect, constitute a PC warrant? And, if that's the case, who cares if a "search" (however narrowly or broadly defined) took place?

In any event, looks like CJLF will be busy drafting an amicus brief.

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