The Volokh Conspiracy

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Public Utility's Recording of Home Energy Consumption Every 15 Minutes Is A "Search," Seventh Circuit Rules

An important ruling in the wake of Carpenter v. United States.


In a fascinating new decision, Naperville Smart Meter Awareness v. City of Naperville, the Seventh Circuit has held that a public utility commits a "search" of a home when it records every 15 minutes how much electricity the utility is providing the home, at least until the smart readers that enable this data collection come into general public use. At the same time, the court says, the utility's search of the home is reasonable and therefore permitted without any cause or suspicion. The Seventh Circuit's analysis relies on Carpenter v. United States for a significant step in its reasoning. Given that, the new decision is an interesting measure of where Fourth Amendment law may be going in the post-Carpenter era.

I. The Facts

First, the facts. The City of Naperville provides electricity to its residents. The City received a grant to update the old analog electricity meters with new digital meters. The old meters were the traditional kind that you have to read in person every once in a while. The new meters are digital and can be programmed to send back the energy consumption at the home at short intervals. The city installed the new meters at every home, and it programmed its meters to record consumption at 15 minute intervals and to keep the consumption records for three years. (It is unclear to me fro the options if the meters read only the overall amount of consumption over the most recent 15-minute period or the instantaneous rate of consumption every 15 minutes, but I'm guessing it's the former.)

A group of citizens sued the city, arguing that the city's recording how much energy homes were consuming violated the people's Fourth Amendment rights. Specifically, the citizens argued that if you know how much electricity a home is using every 15 minutes, you can get some ideas as to what is happening inside the home. You might be able to tell when people are home, when they're awake, and when they are doing things that require a lot of electricity such as cooking dinner or charging up their electric cars. This surveillance searched the homes and violated the Fourth Amendment, they claimed.

II. The Legal Ruling

In a decision by Judge Kanne, joined by Chief Judge Wood and Judge Bauer, the Seventh Circuit agreed that the city's close monitoring of how much energy the city was giving to homes was a "search" of those homes. Much of the reasoning was based closely on Kyllo v. United States, in which the Court held that directing a thermal-imaging device to get a temperature reading of the home was a search. Obtaining electricity readings of a home was a search much like using a thermal imaging device:

"Where … the Government uses a device that is not in general public use, to explore details of the home that would previously have been unknowable without physical intrusion, the surveillance is a 'search.'" Id. at 40. This protection remains in force even when the enhancements do not allow the government to literally peer into the home. In Kyllo, for instance, the intrusion by way of thermal imaging was relatively crude—it showed that "the roof over the garage and a side wall of [a] home were relatively hot compared to the rest of the home and substantially warmer than neighboring homes in the triplex." Id. at 30. The device "did not show any people or activity within the walls of the structure" nor could it "penetrate walls or windows to reveal conversations or human activities." Id (quoting Supp.App. to Pet. for Cert. 39–40). Nevertheless, the Supreme Court held that law enforcement had searched the home when they collected thermal images. Id. at 40.

The technology-assisted data collection that Smart Meter Awareness alleges here is at least as rich as that found to be a search in Kyllo. Indeed, the group alleges that energy-consumption data collected at fifteen-minute intervals reveals when people are home, when people are away, when people sleep and eat, what types of appliances are in the home, and when those appliances are used.5 (R. 102-1 at 14.) By contrast, Kyllo merely revealed that something in the home was emitting a large amount of energy (in the form of heat).

The Seventh Circuit then noted Kyllo's apparent limitation to devices not in general public use. Digital meters are not in general public use, at least yet, so their use is a search today even if it may not be a search in the future:

Under Kyllo, however, even an extremely invasive technology can evade the warrant requirement if it is "in general public use." Id. at 40. While more and more energy providers are encouraging (or in this case forcing) their customers to permit the installation of smart meters, the meters are not yet so pervasive that they fall into this class. To be sure, the exact contours of this qualifier are unclear—since Kyllo, the Supreme Court has offered little guidance. But Kyllo itself suggests that the use of technology is not a search when the technology is both widely available and routinely used by the general public. See id. at 39 n.6 (quoting California v. Ciraolo, 476 U.S. 207, 215 (1986) ("In an age where private and commercial flight in the public airways is routine, it is unreasonable for respondent to expect that his marijuana plants were constitutionally protected from being observed with the naked eye from an altitude of 1,000 feet.")). Smart meters, by contrast, have been adopted only by a portion of a highly specialized industry.

At this point you're probably thinking, hey, wait a second. In Kyllo, the government brought a new tool to the home and used it to obtain the heat profile from inside the home without the homeowner's awareness. That's really different from the facts here. The public utility is just keeping records on what the public utility is doing. That is, the public utility is connected to the home, and the people inside the home are using electricity by drawing it from the public utility. At bottom, the utility was just monitoring how much electricity the utility was transfering to the home. In traditional Fourth Amendment law, that would make a big difference. That's the basic idea of the undercover agent cases and the third-party doctrine based on them: When you have a transaction with someone, the person you're transacting with is allowed to record what they're experiencing without their experience being a "search" of you.

But that's not an issue under Carpenter, the Seventh Circuit holds. Everyone in Naperville has to use a smart meter for electricity. Thus a person's interactions with the government public utility aren't voluntary, and the fact of the government recording its part of the transaction is still a search:

The third-party doctrine rests on "the notion that an individual has a reduced expectation of privacy in information knowingly shared with another." Carpenter, 138 S. Ct. at 2219. But in this context, a choice to share data imposed by fiat is no choice at all. If a person does not—in any meaningful sense—"voluntarily 'assume the risk' of turning over a comprehensive dossier of physical movements" by choosing to use a cell phone, Carpenter, 138 S. Ct. at 2220 (quoting Smith, 442 U.S. at 745), it also goes that a home occupant does not assume the risk of near constant monitoring by choosing to have electricity in her home. We therefore doubt that Smith and Miller extend this far.

(Even there, the court is unsure the third-party doctrine is relevant: "As a threshold matter, Smart Meter Awareness challenges the collection of the data by Naperville's public utility. There is no third party involved in the exchange," the court notes.) As I understand the reasoning, the city's recording the city's transmission of electricity to the home is a "search" of the home because it might enable inferences as to what is happening inside the home that a user can't escape. As in Carpenter, the switch to a new technology enabled more surveillance than before and the extra surveillance makes the closer monitoring—even the government's monitoring of what the government's service is doing—a search:

The ever-accelerating pace of technological development carries serious privacy implications. Smart meters are no exception. Their data, even when collected at fifteen-minute intervals, reveals details about the home that would be otherwise unavailable to government officials with a physical search. Naperville therefore "searches" its residents' homes when it collects this data.

Next the Seventh Circuit rules that although the utility monitoring is a search, it is a reasonable search and is therefore constitutional. The court applies a reasonableness balancing approach instead of the warrant requirement because it is a non-criminal search program. Under that balancing approach, the court rules, the searches are reasonable. First, monitoring electricity use at 15-minute intervals "is far less invasive than the prototypical Fourth Amendment search of a home." The city isn't trying to collect evidence of crime, and it has promised that it won't disclose the data to anyone without a court order. On the other hand, smart meters are socially beneficial. They're cheaper because they don't require in-person visits and the encourage energy efficiency and the stability of the electricity grid. Thus the 15-minute-interval searches are reasonable.

III. My Initial Reactions

Fascinating case. A few tentative thougts about the opinion:

(1) A key part of the reasoning of the case seems to be the Seventh Circuit's acceptance of the idea that 15-minute-interval monitoring of electricity usage can reveal precise details of what is happening inside the home. There's no evidence in the record to support that, as far as I can tell. Rather, it seems to be a claim based on the plaintff's complaint, which in turn cites some academic journal studies. Procedurally, the appeal is from a denial of a motion to amend a complaint. The appellate court is therefore applying the Rule 12(b)(6) sufficiency standard and treating the complaint as true. Given that the search analysis hinges on how much information the smart meter can reveal, I found it a little odd that the court didn't emphasize this procedural posture. Instead, the court just presents its characterizaton of the findings of the academic journals as the truth about smart meters for every home.

Granted, Carpenter suggests that "facts" and "the record" may be somewhat antiquated concepts in the new Fourth Amendment world. If Carpenter can apply the Fourth Amendment to future facts as predicted by judges, I suppose Naperville can treat characterizations of journal articles in a complaint, as well as some stuff they found on the Internet (see footnote 5), as universal truth. But it seemed odd to me that the Seventh Circuit didn't struggle a little more with the uncertainty about what the smart meters do, or at least explain that this was just a claim from the complaint rather than something based on an actual search that occurred in this case.

(2) Another interesting aspect of Naperville is that I gather it's the recording of the information that matters. That is, the government is delivering electricity to each home at a certain rate. The data of how much it is delivering has always existed on the government's network. What makes it a search now, as I understand the opinion, is the cumulative effect of the government recording and saving that information at relatively short intervals for what the utility can learn about its users. Use of the meters "reveals details about the home that would be otherwise unavailable to government officials with a physical search" in the sense that the government now has collected the data in a way it can use, not in the sense that it wasn't there on the government's network before.

(3) An obvious question is whether the search analysis is a correct application of the principles of Carpenter. At least off the top of my head, I'm not sure there's an answer. It's an extension of Carpenter, but there's so much uncertainty in Carpenter that it becomes hard to say if the Seventh Circuit is applying it correctly.

(4) It's also interesting that the Seventh Circuit seems to think that if there is no third-party, then that is an argument for Fourth Amendment rights rather than against them. When the City argued the third-party doctrine, the Seventh Circuit at first says that the third-party doctrine may not be applicable at all because there is no third-party. This was disclosure directly to the government, not to a third party that the government then approached. This is a bit backwards, I think. The third-party doctrine is an application of the undercover agent cases, like Hoffa v. United States, in which the person is talking directly to a government actor. Your Fourth Amendment rights aren't violated when you share information directly to a government agent, the undercover agent cases say. The third-party doctrine just applies the same principle to disclosure to a private actor who then hands over the information to the government. In my experience, the critics of the third-party doctrine are usually still on board with the undercover agent cases. They just don't want the same principle to apply to disclosure to a private party not yet acting under government direction. Given that, you would think that the fact that the government here was just recording its own part of the transaction of the transfer of electricity to people was really about the undercover agent cases. It's somewhat tougher ground to challenge, I would have thought.

(5) The "general public use" part of Naperville is fascinating, too. Again, there are no facts brought out here. The ruling seems more a matter of judicial intuition, much like in Kyllo. But I gather its effect is to say that governments have to be careful in how they introduce smart meters, but that after they are rolled out there will be no limitations on their use. Right now, the court says, smart meters are pretty rare, so the government has to be reasonable and balanced and careful with what it does with smart meter data to make the collective searches reasonable. But after smart meters become common, they'll be in general public use and there will be no limitations on their use. Seems like an odd constitutional framework, but so it goes.