This morning the Supreme Court heard argument in Carpenter v. United States, one of the most important 4th Amendment cases in recent history.

The Fourth Amendment to the U.S. Constitution reads:

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

At issue in Carpenter is the question of whether the Fourth Amendment protects against the warrantless search and seizure of historical cell phone data revealing the location of a cell phone over 127 days. Below I will outline the background of the case, the relevant doctrine, and what the justices’ questions today reveal about what they might be thinking.

Background

Timothy Carpenter and other suspects conducted a series of armed robberies in Michigan and Ohio in 2010 and 2011. Investigators sought cell-phone location data related to Carpenter and other suspects, asking judges for orders that would allow them to examine five-months worth of cell phone location data. They did not need to seek a warrant. Rather, they sought orders pursuant to the Stored Communications Act, which allows the government to obtain an order if investigators offer “specific and articulable facts showing that there are reasonable grounds to believe” that the data “are relevant and material to an ongoing criminal investigation.”

Using cell phone records, investigators could place Carpenter near “the robberies around the time the robberies happened.” Carpenter was arrested and found guilty of robbery, using a firearm during the course a federal crime, as well as aiding and abetting. Thanks to mandatory minimums, all of these convictions added up to a sentence of almost 116 years:

The jury convicted Carpenter of six robberies in violation of the Hobbs Act, 18 U.S.C. § 1951(a), and five separate violations of 18 U.S.C. § 924(c) for using or carrying a firearm in connection with a federal crime of violence and aiding and abetting. All but the first of the § 924(c) convictions carried mandatory consecutive minimum sentences of 25 years each. As a result, the court sentenced Carpenter to nearly 116 years’ imprisonment (1,395 months).

Carpenter appealed to the Sixth Circuit, which found that government had not conducted a Fourth Amendment search because Carpenter did not have a reasonable expectation of privacy in the cell phone location data he had voluntarily handed over to his cell service provider. Carpenter appealed to the Supreme Court, which heard oral arguments for the case today.

Doctrine at Issue

Since the 1967 Supreme Court case Katz v. United States courts have interpreted the word “search” in the Fourth Amendment to mean something quite different to what those of us who aren’t judges think it means. To most people, the word “search” means something like “look into,” “discover,” or “examine.”

But according to the “reasonable expectation of privacy” test developed in Justice Harlan’s solo concurrence in Katz, a Fourth Amendment search has taken place if the government violates your subjective expectation of privacy that society is prepared to accept as reasonable. This test has guided judges considering Fourth Amendment cases ever since.

In United States v. Miller (1976) and Smith v. Maryland (1979) the Supreme Court codified the “Third Party Doctrine.” Under the Third Party Doctrine, individuals do not have a reasonable expectation of privacy to information they voluntarily expose to third parties such as phone companies and banks.

In her solo concurrence in arguably the most significant Fourth Amendment case to be decided this century, United States v. Jones (2012), Justice Sotomayor took aim at the Third Party Doctrine, writing:

I would ask whether people reasonably expect that their movements will be recorded and aggregated in a manner that enables the Government to ascertain, more or less at will, their political and religious beliefs, sexual habits, and so on. I do not regard as dispositive the fact that the Government might obtain the fruits of GPS monitoring through lawful conventional surveillance techniques. […] I would also consider the appropriateness of entrusting to the Executive, in the absence of any oversight from a coordinate branch, a tool so amenable to misuse, especially in light of the Fourth Amendment’s goal to curb arbitrary exercises of police power to and prevent “a too permeating police surveillance,” United States v.Di Re, 332 U. S. 581, 595 (1948).

More fundamentally, it may be necessary to reconsider the premise that an individual has no reasonable expectation of privacy in information voluntarily disclosed to third parties.

Today’s Argument

My guess is that the Court will rule in favor of Carpenter. However, today’s oral arguments don’t provide a clear idea about what this ruling will look like and what exception to the Third Party Doctrine might emerge. You can read the transcript of the arguments here.

The ACLU’s Nathan Wessler, who represented Carpenter, made sure to point out during an exchange with Justice Kennedy that he was not asking the Court to overturn Miller and Smith, arguing that the information gathered from cell phone location data is more sensitive than information individuals provide banks. He went on to argue that there should be a distinction between “long term” and “short term” location tracking, with “long term” location observations constituting a Fourth Amendment search.

After all, in Jones five justices (Alito, Kagan, Breyer, Ginsburg, and Sotomayor) wrote or signed onto concurring opinions that endorsed such a distinction. Yet Wessler’s proposed 24 hour line was met with skepticism by Justices Sotomayor and Ginsburg. Justice Sotomayor pointed out that cell phone tracking that lasts for fewer than 24 hours can reveal intimate details about a person’s life. Justice Kagan noted that Carpenter and Jones both involved the continuous tracking of suspects, which suggests she’s prepared to consider the tracking in Carpenter as a violation of Carpenter’s reasonable expectation of privacy.*

One of the most interesting exchanges of today took place between Justice Gorsuch and Deputy Solicitor General Michael Dreeben, with Gorsuch positing a hypothetical highlighting how a property rights approach might be used to analyze the case:

Let’s say I have a property right in the conversion case I posited with your colleague. so that if someone were to steal my location information from T‑Mobile I’d have a conversion claim, for example, against them for the economic value that was stolen. Wouldn’t that, therefore, be a search of my paper or effect under the property-based approach approved and reminded us in Jones?

Gorsuch continued a little later:

JUSTICE GORSUCH: Under my hypothetical, you have a property right in this information. Would it be a search of my paper and effect? Yes or no.

MR. DREEBEN: I am not sure. And the reason that I am not sure is there has never been a property right recognized in information that’s conveyed to a business of this character.

Justice Gorsuch is playing with an interesting theory here. Andrew Guthrie Ferguson, a professor of law at the University of the District of Columbia, David A. Clarke School of law, has explored a similar idea in a paper that defends a theory of “informational curtilage.” The newest member of the court embracing a property rights argument in favor of Carpenter is an intriguing prospect, and could result in a fascinating concurring opinion.

If today’s oral arguments are anything to go by, a majority of the justices seem prepared to rule that the Fourth Amendment does not allow for the warrantless search and seizure of historical cell phone data revealing the location of a cell phone over 127 days. What theories the justices use to buttress their arguments remains to be seen.

*I updated this paragraph to clarify Justice Kagan’s views and to note that Justices Ginsburg and Sotomayor were skeptical of the proposed 24 hour line.