As the country’s new Congress settles into its term, several technology issues are coming to the forefront. A number of Senators recently questioned the Department of Justice over how it is collecting cellphone-location data in the wake of the Supreme Court’s landmark Carpenter decision. Carpenter v. United States, 138 S. Ct. 2206 (2018). The House of Representatives is considering a renewed version of legislation that would strengthen the security of “Internet of Things” technologies used by the federal government. And politicians and pundits throughout Capitol Hill are asking whether this will be the year that comprehensive federal privacy legislation becomes law. As it turns out though, some of the nation’s top courts are already tackling these tough issues. In fact, the Seventh Circuit’s opinion last year in Naperville Smart Meter Awareness v. City of Naperville, 900 F.3d 521 (7th Cir. 2018), has received relatively little reporting, but its impact will be broad when it comes to how courts interpret the Fourth Amendment in the era of big data.

In Naperville, the Seventh Circuit heard an appeal concerning the city’s “smart meter” program. Without residents’ permission, Naperville had been replacing traditional energy meters on its grid with “smart meters” for homes. Each smart meter collected thousands of readings a month, as opposed to just the previous single monthly readings. According to the plaintiffs, the repeated readings of the smart meters collected data at such a granular level that they revealed what appliances were present in homes and when they were used. Considering the potential privacy impact, the Seventh Circuit found that Naperville’s collection of smart meter data from residents’ homes constituted a “search” under the Fourth Amendment.

Importantly, the Court applied last year’s Supreme Court decision Carpenter, which had found that a court order to a wireless carrier for historical cell site location data constituted a search and required a warrant supported by probable cause. As in Carpenter, the Seventh Circuit found the residents’ lack of consent to the collection of the comprehensive smart meter data was key to rendering that collection a search. Having found that the smart meter data’s collection was a search under the Fourth Amendment, the Court then asked whether the search was reasonable. In answering that question in the affirmative, the Court considered the search’s ultimate purpose. That is, the search was being performed by a public utility to strengthen the city’s energy grid and reduce costs—not by an enforcement division. Because the city conducted the search with no enforcement intent, the Court found it reasonable.

Although the Seventh Circuit’s decision ultimately let the city’s practices stand, its analysis reflects the heightened scrutiny with which consumers, courts, and the plaintiffs’ bar are approaching big data collection. Private companies and government entities are increasingly in possession of ever-growing quantities of data that reveal, in the words of Chief Justice Roberts, the “privacies of life.” The proximity and persistence of connected devices like Naperville’s smart meters enable them to generate these troves of data, and thus new and hopefully helpful insights.

At the same time, what makes this data so appealing is also what makes it qualitatively different, at least in the Seventh Circuit. Pre-Carpenter precedent often held that information collected from “analog” meters by utility companies is not protected by the Fourth Amendment. See, e.g., United States v. McIntyre, 646 F.3d 1107, 1110 (8th Cir. 2011) (finding defendant did not have a reasonable expectation of privacy protected by the Fourth Amendment in monthly cumulative electricity usage readings). What made this case different to the Court was the intimate insights one could gain from the smart meters about someone’s home activities, e.g., when and for how long someone uses their microwave.

While the facts in Naperville were unique, that opinion together with Carpenter make clear that courts are carefully evaluating privacy rights and constitutional protections when it comes to the collection of big data. Whether and how the federal legislature dives into the fray remains to be seen.