CA4 (en banc 8-7): Baltimore’s aerial surveillance program is a “search” under Carpenter

The Baltimore Police Department’s aerial surveillance program is a search under Carpenter because of the detail it provides and the viewers of the information can go back in time. Leaders of a Beautiful Struggle v. Baltimore Police Department, 2021 U.S. App. LEXIS 18868 (4th Cir. June 24, 2021) (en banc; 8-7):

The Plaintiffs—a group of grassroots community advocates in Baltimore—moved to enjoin implementation of the Aerial Investigation Research (“AIR”) program, a first-of-its-kind aerial surveillance program operated by the Defendants—the Baltimore Police Department (“BPD”) and Commissioner Michael Harrison.

… [Mootness omitted]

On the merits, because the AIR program enables police to deduce from the whole of individuals’ movements, we hold that accessing its data is a search, and its warrantless operation violates the Fourth Amendment. Therefore, we reverse and remand.

. . .

Carpenter applies squarely to this case. See id. at 2215–19. More like the CSLI in Carpenter and GPS-data in Jones than the radio-beeper in Knotts, the AIR program “tracks every movement” of every person outside in Baltimore. See id. at 2215–19. Because the data is retained for 45 days—at least—it is a “detailed, encyclopedic,” record of where everyone came and went within the city during daylight hours over the prior month-and-a-half. See id. Law enforcement can “travel back in time” to observe a target’s movements, forwards and backwards. See id. at 2218. Without technology, police can attempt to tail suspects, but AIR data is more like “attach[ing] an ankle monitor” to every person in the city. See id. “Whoever the suspect turns out to be,” they have “effectively been tailed” for the prior six weeks. See id. (“[P]olice need not even know in advance whether they want to follow a particular individual, or when.”). Thus, the “retrospective quality of the data” enables police to “retrace a person’s whereabouts,” granting access to otherwise “unknowable” information. See id.

We do not suggest that the AIR program allows perfect tracking of all individuals it captures across all the time it covers. Though data is collected in 12-hour increments, the tracks are often shorter snippets of several hours or less. Still, the program enables photographic, retrospective location tracking in multi-hour blocks, often over consecutive days, with a month and a half of daytimes for analysts to work with. That is enough to yield “a wealth of detail,” greater than the sum of the individual trips. See Jones, 565 U.S. at 415–17 (Sotomayor, J., concurring) (suggesting people do not expect “that their movements will be recorded and aggregated in a manner that enables the government to ascertain” details of their private lives). It enables deductions about “what a person does repeatedly, what he does not do, and what he does ensemble,” which “reveal[s] more about a person than does any individual trip viewed in isolation.” United States v. Maynard, 615 F.3d 544, 562–63 (D.C. Cir. 2010). Carpenter held those deductions go to the privacies of life, the epitome of information expected to be beyond the warrantless reach of the government. 138 S. Ct. at 2214, 2218. And here, as there, the government can deduce such information only because it recorded everyone’s movements. See id. at 2218.

Therefore, because the AIR program opens “an intimate window” into a person’s associations and activities, it violates the reasonable expectation of privacy individuals have in the whole of their movements. See id.at 2218–19. The district court reached the opposite conclusion because it believed, as Defendants argue on appeal, that the AIR program is capable of only short-term tracking. It emphasized that AIR images show people only as “a series of anonymous dots traversing a map of Baltimore,” and the planes do not fly over night, so “gaps in the data will prohibit the tracking of individuals over the course of multiple days.” See, e.g., Beautiful Struggle, 456 F. Supp. 3d at 714, 716.

But those facts don’t support the district court’s conclusion. The datasets in Jones and Carpenter had gaps in their coverage, too. The GPS data in Jones only tracked driving in a specific car, precise to “within 50 to 100 feet.” See 565 U.S. at 404. The raw CSLI in Carpenter was a log of thousands of estimated location points from which a cell phone pinged a cell tower. 138 S. Ct. at 2211–12, 2218 (“[The CSLI] placed [the suspect] within a wedge-shaped sector ranging from one-eighth to four square miles.”). Yet, in both cases, the surveillance still surpassed ordinary expectations of law enforcement’s capacity and provided enough information to deduce details from the whole of individuals’ movements. See id. at 2217–18 (“[Police] might have pursued a suspect for a brief stretch, but doing so ‘for any extended period of time was difficult and costly and therefore rarely undertaken’ …. [and] attempts to reconstruct a person’s movements were limited by a dearth of records and the frailties of recollection.”) (quoting Jones, 465 U.S. at 429).

The same is true here. That Defendants chose to limit data collection to daylight hours and a certain resolution does not make the AIR program equivalent to traditional, short-term surveillance. AIR data is a photographic record of movements, surpassing the precision even of GPS data and CSLI, which record variable location points from which movements can be reconstructed. And while the coverage is not 24/7, most people do most of their moving during the daytime, not overnight. Likewise, many people start and end most days at home, following a relatively habitual pattern in between. These habits, analyzed with other available information, will often be enough for law enforcement to deduce the people behind the pixels. And if a track is interrupted by sunset, police will at least sometimes be able to re-identify the same target over consecutive days. For example, law enforcement could use AIR data to track a person’s movements from a crime scene to, eventually, a residential location where the person remains. They could then look through time and track movements from that residence. They could use any number of context clues to distinguish individuals and deduce identity. After all, the AIR program’s express goal is to identify suspects and witnesses to help BPD solve crimes.

The record supports these intuitive conclusions. Plaintiffs submitted research showing that, because people’s movements are so unique and habitual, it is almost always possible to identify people by observing even just a few points of their location history. The district court disregarded Plaintiffs’ study because it was based on CSLI. But the source of the underlying location data is entirely irrelevant: the study shows that identity is easy to deduce from just a few random points of an individual’s movements. Whether those points are obtained from a cell phone pinging a cell tower or an airplane photographing a city makes no difference. Beyond Plaintiffs’ study, common sense and ample authority over the last decade corroborates this conclusion. Further, the AIR program does not deduce identity from randomly selected location points, like in a research study. Rather, the context of specific investigations narrows the pool of possible identities. Police can cross-reference against publicly available information and, even more valuably, their own data systems. PSS can enhance the process by integrating BPD systems—like its CitiWatch camera network, license plate readers, and gunshot detectors—into its “iView software,” “mak[ing] all the systems work together.” J.A. 71, 132. For example, if the tracking of a car is interrupted, license plate readers could help relocate it in the AIR data over the following days. Yet the district court disregarded these capabilities, reasoning that Plaintiffs were “lump[ing] together discrete surveillance activities as one Fourth Amendment ‘search.’” Beautiful Struggle, 465 F. Supp. 3d at 716.

Reason: Appeals Court Rules Aerial Police Tracking of Citizens Violates Fourth Amendment by Scott Shackford (“Baltimore kept tabs on citizens’ movement across 90 percent of the city, without a warrant, to investigate crimes.”)

Techdirt: Appeals Court Reverses Earlier Decision, Says Baltimore’s Aerial Surveillance Program Is Unconstitutional by Tim Cushing

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