The Legal Advocate

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Carpenter v. United States (2018)

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Written by NITA guest blogger Brent Newton

On June 22, 2018, the Supreme Court, by a vote of 5-4, issued its much-anticipated decision in Carpenter v. United States.  Carpenter was convicted of multiple robberies based in part on evidence that, at the time of four of the robberies, his cell phone had sent signals to numerous cell towers located near the places where the robberies occurred.  Law enforcement officers had obtained over 100 days of cell-tower records from Carpenter’s two wireless carriers without first securing a search warrant based on probable cause.  The Supreme Court reversed Carpenter’s convictions.  It held law enforcement officers’ access to seven days or more of historical cell-tower records from a wireless carrier constitutes a “search” under the Fourth Amendment in that a cell phone account holder has a “legitimate expectation of privacy in the record of his physical movements.”  Because a Fourth Amendment search ordinarily requires a search warrant based on probable cause, the Court held that the officers obtained Carpenter’s cell-tower records in an unconstitutional manner.

Chief Justice Roberts wrote the majority opinion and was joined by Justices Ginsburg, Breyer, Kagan, and Sotomayor.  Four justices – Kennedy, Thomas, Alito, and Gorsuch – each dissented in separate opinions.

The majority opinion relied in significant part on the two concurring opinions in the Court’s 2012 decision in United States v. Jones.  The majority in Jones held that the warrantless placement of a GPS tracking device on a defendant’s car, which was thereafter monitored 24/7 for over a month, was a “search” under the Fourth Amendment.  The majority in Jones relied on the defendant’s property interest in the car rather than his privacy interest related to having his car’s movements tracked by the GPS device.  Conversely, the two concurring opinions in Jones focused instead on the Jones’s privacy interest in not having his every movement tracked for over a month. 

The majority opinion in Carpenter relied on the concurring opinions in Jones for the proposition that a person has “reasonable expectation of privacy in the whole of their physical movements” over an extended period of time.  Officers’ access to historical cell-tower records violates that reasonable expectation of privacy because it is a “sweeping mode of surveillance” that allows officers to engage in “near perfect surveillance, as if [they] had attached an ankle monitor to the phone’s user.”  Such an “all-encompassing record of the [phone’s user’s] whereabouts” thus is a “search” under the Fourth Amendment, requiring a warrant based on probable cause.

The Court did not hold that law enforcement officers need to obtain a warrant when they access short-term cell-location evidence (i.e., less than seven days’ worth of records).  “[W]e need not decide whether there is a limited period for which the Government may obtain an individual’s historical [cell-tower records] free from Fourth Amendment scrutiny, and if so, how long that period might be.  It is sufficient for our purposes today to hold that accessing seven days of [cell-tower records] constitutes a Fourth Amendment search.”   The majority also did not address whether “real-time” cell-tower monitoring of a suspect’s phone constitutes a “search.”  Those situations will likely be addressed in future cases.

Finally, the Court was clear that it was not overruling its prior cases holding that a person has no Fourth Amendment privacy interest in normal “third-party” business records (such as bank transactions or ordinary phone records).  The Court stated that “there is a world of difference between the limited types of personal information [in such third-party records] and the exhaustive chronicle of location information casually collected by wireless carriers today [in cell-tower records].”

Carpenter is a landmark Fourth Amendment decision.  It requires that law enforcement officers obtain a search warrant based on probable cause before they can access a suspect’s historical cell-tower records of a duration of seven days or more.  Based on its adoption of the reasoning of the two concurring opinions in Jones as the holding of the Court, the majority opinion in Carpenter also has broader implications for officers’ long-term GPS monitoring of suspects’ movements.  Any such monitoring of seven days or more also now requires a search warrant even if officers did not place a GPS device on the suspect’s person or property.



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