On Wednesday 29 November 2017, the Supreme Court of the United States (“the Court”) heard oral argument in Carpenter v. the United States. The issue in Carpenter is whether a warrantless seizure and search of records showing the location of a person’s mobile phone (Cell-Site Location Information – CSLI) over the course of 5 months is permitted by the Fourth Amendment of the United States Constitution.

However, the case is of wider significance as it offers the Court the opportunity to define the scope of constitutional privacy protections in an age of mobile phones, internet, and bulk data.

The Petitioner, Timothy Carpenter, was convicted for his role in a series of armed robberies in 2010-2011. After obtaining his cell-phone records (CSLI) for the relevant five-month period, the State was able to show Carpenter to be in the vicinity of the robberies. Carpenter’s CSLI had been acquired by the State following an application made under the Stored Communications Act 1986 (“the Act”). The Act allows cell-phone providers to disclose CSLI of its customers if the State can show “specific and articulable facts showing that there are reasonable grounds to believe” that the requested records “are relevant and material to an ongoing criminal investigation.”

Carpenter argued that the records had been acquired without a warrant and in violation of his Fourth Amendment rights and as such should be suppressed.

The Fourth Amendment provides that:

“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.”

The trial and appellate courts disagreed that acquiring the records constituted a Fourth Amendment search. The courts applied the “third party doctrine”, which provides that the Fourth Amendment generally does not apply to situations where a person voluntarily shares their information with a third party. According to the lower courts, by using his cell-phone Carpenter had voluntarily connected to a nearby cell tower and as such his CSLI was unprotected by the Fourth Amendment.  The key authorities for the doctrine are two of the Court’s cases from the 1970s, United States v. Miller and Smith v. Maryland. In the former, the Court held that bank records only contained “information voluntarily conveyed to the banks and exposed to their employees in the ordinary course of business”. In the latter, and the court allowed a phone company to record the phone numbers dialled by a robbery suspect on the similar basis that he had voluntarily used the company’s telephone service and had thus provided the company with the information of who he had attempted to phone (the records did not show whether the calls had been connected).

Before the Court, Carpenter argues that the acquisition of longer-term historical CSLI constitutes a search. The primary argument for this is that a person has a “reasonable expectation of privacy” in relation to longer-term historical CSLI.

Carpenter argues that the Court should recognise the “sea change in technology” that made possible the search and to avoid the “wooden application of principles from a bygone era”. In Carpenter’s view, more recent precedent has established the principle that the State cannot use modern technology to shrink privacy rights (“the anti-shrinkage principle”). Moreover, Carpenter argues that even if Smith and Miller are treated as good authority, CSLI does not satisfy the requirements of the third party doctrine.

Carpenter relies on a line of Supreme Court authority, which culminated in United States v. Jones, for the anti-shrinkage principle. In Jones, five concurring justices held that GPS tracking constitutes a search, as historically people would never have expected the State to be able to access records of their movements over a sustained period of time. Carpenter asserts that CSLI records are directly analogous to GPS data as it allowed the State to deduce his location at specific points. However, the State argues that the data is not accurate enough to pinpoint movements to the specificity of GPS tracking.

Carpenter also argues that the third party doctrine has never applied to highly sensitive information. This line of reasoning seemed to resonate with Justices Sotomayor and Breyer during oral argument. Sotomayor noted that the Court had not extended the third party rule to allow police officers to obtain medical records without patient consent. Sotomayor queried whether a person’s location over a five month period mind similarly be sensitive information to which the third party doctrine does not apply.  Justice Breyer posited a possible distinction between “highly personal” data, such as medical records and CSLI retained over a sustained period of time, and commercial information, such as bank records. Justice Breyer’s attempt here to draw a line is unlikely to persuade his fellow justices, given that “personal” and “commercial” are not mutually exclusive as bank records could reveal highly personal information about a person.

Carpenter posits that CSLI is not “voluntarily” conveyed and thus the third party doctrine does not apply. Carpenter argues that a smartphone is the “nerve center used to organize and manage virtually every aspect of a person’s life.” As such, using a phone is so “central to one’s self-expression, well-being, safety, and livelihood” it is not a volitional act to use one. Carpenter also asserts that while people are aware that their phones have to connect to cell towers, few if any are likely to know that every such connection is recorded and maintained, even when a person switches off the location services on their phone. People do not receive records from their companies that this data is being recorded, unlike bank records. However, this argument did not seem to convince Justice Kennedy, who remarked that “if I know it, everybody does,” in relation to cell-phone companies retaining CSLI.

Carpenter’s primary arguments are based on the predominant view that the Fourth Amendment protects a reasonable expectation of privacy. However, there is a “rival” approach to the Fourth Amendment based on the protection of property rights. The argument was not made by Carpenter in the Sixth Circuit, which in obiter dismissed the idea that Carpenter had a property interest in his CSLI as an absurdity. However, now Carpenter (admittedly somewhat half-heartedly, at least in written submissions) argues that he has a property interest in his CSLI. He argues that the Telecommunications Act 1996 provides cell phone users with the right to exclude other from their CSLI and to limit its use.  Despite the cell phone company retaining the possession of, and a limited right to use, the records, Carpenter still possesses some of the “bundle of sticks” and as such has a property right in the CSLI that the Fourth Amendment protects.

Despite the lack of prominence the property-based approach was given in written submissions by Carpenter, it could provide a coherent way for the Court to redefine the scope of Fourth Amendment in the digital age.

The property-based approach lost favour in the second half of the twentieth century. The most famous proponent of the approach was Justice Scalia. While Justice Scalia was arguably the most conservative of the Court during his tenure (for example in his dissent in Obergefell v. Hodges, the landmark equal marriage judgment, he wrote that “if I ever joined an opinion for the Court that began: “The Constitution promises liberty to all within its reach, a liberty that includes certain specific rights that allow persons, within a lawful realm, to define and express their identity,” I would hide my head in a bag”)  he was also one of the staunchest defenders of the Fourth Amendment. It appears that his replacement on the Court, Trump-nominee Justice Gorsuch, might have picked up his predecessor’s originalist, property-based approach Fourth Amendment mantle.

During oral argument, Justice Gorsuch raised the possibility of the property-based approach:

“…putting aside reasonable expectation for just a moment, what do we know about what state law would say about this information? Say a thief broke into T-Mobile, stole this information and sought to make economic value of it. Would your client have a conversion claim, for example, under state law?”

Justice Gorsuch has advanced this property-based approach before. In United States v. Ackerman, he found that the State had essentially committed a trespass to chattels by opening Ackerman’s emails and had thus violated the Fourth Amendment. During oral argument in Carpenter, several other Justices seemed to allude to a property- based approach. For example, Chief Justice Roberts referred to cell phone records as being like a “joint venture” with the phone’s owner.

The property-based approach seems likely to attract support from both liberal and conservative justices looking for coherency. Justice Breyer alluded to this when he stated that the case was an “open box- we know not where we go” and asked for assistance from counsel on how the Court should “draw the line”.  During oral argument, the Justices found it difficult to “draw a line” in the reasonable expectation of privacy approach. Society’s expectation of privacy is constantly contracting to reflect the realities of increasingly invasive technology. Therefore, attempting to find a coherent “line” while meaningfully protects privacy might be impossible and necessitate a property-based approach.

There is a certain irony that the originalist, property-based approach to the Fourth Amendment, which was considered outdated in the 1960s, might end up providing an important safeguard to privacy rights in the digital age.