US Supreme Court holds that Cell-Site Data is Generally Protected by the Fourth Amendment

By: Ami Imbrogno

Technology has changed rapidly over the past 50 years.  Indeed, just 15 years ago, most people did not imagine that they would be carrying the entire world wide web in one pocket or purse, or that all of their movements would be tracked via cell phone. As technology has developed, more people have become increasingly concerned about the sheer amount of data that is collected by mobile telephone devices, and how this data could be used to invade their privacy. One of last week’s decisions from the Supreme Court, Carpenter v. United States, addressed how privacy concerns, vast amounts of electronic data, and the Fourth Amendment could intersect.

Eight years ago, a string of robberies took place in Michigan and Northern Ohio. Police obtained phone numbers of some suspects involved in the robberies, and subpoenaed cell-site location information (CSLI) for the numbers, absent a search warrant, which they used as evidence placing Carpenter nearby each of the robberies at the times they occurred.  It is not uncommon for law enforcement to obtain this information, and this type of evidence is sometimes even used in insurance fraud prosecutions.

Under the Stored Communications Act, the police did not need or a warrant supported by probable cause to obtain these records from Carpenter’s cell phone provider, but instead, only needed “reasonable grounds” for believing that the records were “relevant and material to the ongoing investigation.”  Carpenter moved to suppress the CSLI evidence, alleging that it was the product of an illegal search under the Fourth Amendment.  The trial court denied the motion, and the Sixth Circuit affirmed the denial based on a decades-old concept called the “third-party doctrine.”

The third-party doctrine was an eventual product of the Supreme Court’s 1967 landmark decision Katz v. United States.  In Katz, the Court announced the rule that under the Fourth Amendment, a “search” occurs when the government intrudes into a sphere in which one has a reasonable expectation of privacy, so long as society is also prepared to recognize that expectation as reasonable. In Katz, the court determined that one has a reasonable expectation of privacy in a conversation held within a closed telephone booth – a concept that seems foreign to those living in 2018.  Since 1967, Fourth Amendment “search” jurisprudence has been based on Katz. Specifically, in the late 1970s, the Court held in United States v. Miller and Smith v. Maryland that one has no reasonable expectation of privacy in papers or effects that he or she trusts to the hands of a third party – i.e., banking records or records of phone numbers dialed.  Thus, the third-party doctrine was born.

Perhaps recognizing that most people entrust their entire lives to third parties in the digital age (who doesn’t have their emails, schedules, search histories, and location data stored by a third party like Google or Apple?) the Court ruled in Carpenter’s favor and crafted a narrow decision holding that generally, the government’s acquisition of cell-site records constitutes a search under the Fourth Amendment.  Though the records are stored by third parties, cases involving CSLI are inherently different than previous cases involving bank records or dialed phone numbers because they provide a complete picture of a person’s movements for a period extending to five years. And, though CSLI technology was less complete at the time of Carpenter’s arrest and could only provide information about a general area in which a particular mobile device is located, the Court expects that CSLI will only get more precise as technology improves.

The Court was careful to clarify that its decision does not apply to any aspect of technology other than CSLI, and that it was not announcing an opinion relating to security cameras, national security measures, or other forms of technology.  However, Carpenter opens the door for defendants to at least argue that certain types of technological evidence cannot be obtained absent a warrant, if they implicate privacy interests. If the third-party doctrine does not apply to CSLI, to what other types of evidence will courts refuse to apply the doctrine?  What records are so intrusive upon privacy that the third-party doctrine does not apply to them?

Furthermore, the majority opinion in Carpenter was only supported by five of the nine justices.  All four dissenting justices filed separate dissenting opinions.  Justice Gorsuch and Justice Thomas both suggested in their dissents that the Court scrap the “reasonable expectation of privacy” test announced in Katz and consider that the founding fathers originally intended the Fourth Amendment to be a protection of property rights, not a protection of “privacy.” A search would therefore occur when the government searched a person’s “property.”

The ideas set forth by Justice Gorsuch and Justice Thomas were not unlike those espoused by the late Justice Scalia in United States v. Jones (which involved the placement of a GPS tracker on a defendant’s vehicle).  Should these justices persuade other justices to their point of view, or if like-minded justices join the Court, we could see a radical shift in the definition of a “search” under the Fourth Amendment, which would necessitate new rules for when warrants are required prior to a search.

It is also unclear under Carpenter whether police will be able to obtain these records if a third party voluntarily provides them to police, absent solicitation from law enforcement.  Specifically, if an insurance company were to obtain CSLI from a provider, and then the insurance company provides that information to the police absent a police request, will the evidence be available to use in a prosecution of the insured for insurance fraud?  Prior to last Friday, it would be easy to say that the records could likely be used without implicating the Fourth Amendment.  In the wake of Carpenter, however, it is not unforeseeable that a defendant may try to argue that the special character of CSLI bars the police from using the non-solicited records, too.

For the time being, it is clear that under Carpenter, a “search” occurs when the government obtains CSLI.  One must not forget that warrants only need to be obtained for “unreasonable” searches.  The Court did not state how much CSLI data must be sought before a search is considered unreasonable.  In addition, the Court also held that exceptions to the warrant requirement, like exigent circumstances, would still apply to CSLI.

The current best practice for law enforcement in the wake of Carpenter is to obtain a warrant whenever possible when seeking CSLI.  Should the data be needed in exigent circumstances – for example, quickly to save a person’s life – a warrant may not be needed.  However, if an officer has probable cause to support a warrant, and exigent circumstances do not exist, it is best to obtain a warrant, no matter how much data is being requested.  Moreover, law enforcement should not be surprised if searches not backed by warrants are challenged more frequently in courts of law, and may expect to see further changes to the law and procedure down the road.


For more information or questions regarding this article, contact Ami Imbrogno at aimbrogno@mrrlaw.com.

Ami Imbrogno

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