This blog post was cowritten by EFF intern Lauren Yu.

The U.S. Court of Appeals for the Fourth Circuit ruled last week that Baltimore’s use of aerial surveillance that could track the movements of the entire city violated the Fourth Amendment.

The case, Leaders of a Beautiful Struggle v. Baltimore Police Department, challenged the Baltimore Police Department’s (BPD) use of an aerial surveillance program that continuously captured an estimated 12 hours of coverage of 90 percent of the city each day for a six-month pilot period. EFF, joined by the Brennan Center for Justice, Electronic Privacy Information Center, FreedomWorks, National Association of Criminal Defense Lawyers, and the Rutherford Institute, filed an amicus brief arguing that the two previous court decisions upholding the constitutionality of the program misapplied Supreme Court precedent and failed to recognize the disproportionate impact of surveillance, like Baltimore’s program, on communities of color. 

In its decision, the full Fourth Circuit found that BPD’s use and analysis of its Aerial Investigation Research (AIR) data was a warrantless search that violated the Fourth Amendment. Relying on the Supreme Court’s decisions in United States v. Jones and United States v. Carpenter, the Fourth Circuit held that Carpenter—which ruled that cell-site location information was protected under the Fourth Amendment and thus may only be obtained with a warrant—applied “squarely” to this case. The Fourth Circuit explained that the district court had misapprehended the extent of what the AIR program could do. The district court believed that the program only engaged in short-term tracking. However, the Fourth Circuit clarified that, like the cell-site location information tracking in Carpenter, the AIR program’s detailed data collection and 45-day retention period gave BPD the ability to chronicle movements in a “detailed, encyclopedic” record, akin to “attaching an ankle monitor to every person in the city.”

The court further stated that oversurveillance and the resulting overpolicing do not allow different communities to enjoy the same rights

That ability to deduce an individual’s movements over time violated Baltimore residents’ reasonable expectation of privacy. In making that determination, the court underscored the importance of considering not only the raw data that was gathered but also “what that data could reveal.” Contrary to the BPD’s claims that the aerial surveillance data was anonymous, the court pointed to studies that demonstrated the ease with which people could be identified by just a few points of their location history because of the unique and habitual way we all move. Moreover, the court stated that when this data was combined with Baltimore’s wide array of existing surveillance tools, deducing an individual’s identity became even simpler.

The court also recognized the racial and criminal justice implications of oversurveillance. It noted that although mass surveillance touches everyone, “its hand is heaviest in communities already disadvantaged by their poverty, race, religion, ethnicity, and immigration status,” and that the impact of high-tech monitoring is “conspicuous in the lives of those least empowered to object.” The court further stated that oversurveillance and the resulting overpolicing do not allow different communities to enjoy the same rights: while “liberty from governmental intrusion can be taken for granted in some neighborhoods,” others “experience the Fourth Amendment as a system of surveillance, social control, and violence, not as a constitutional boundary that protects them from unreasonable searches and seizures.”

In a powerful concurring opinion, Chief Judge Gregory dug deeper into this issue. Countering the dissent’s assumption that limiting police authority leads to more violence, the concurrence pointed out that Baltimore spends more per capita on policing than any comparable city, with disproportionate policing of Black neighborhoods. However, policing like the AIR program did not make the city safer; rather, it ignored the root issues that perpetuated violence in the city, including a long history of racial segregation, redlining, and wildly unequal distribution of resources.

We are pleased that the Fourth Circuit recognized the danger in allowing BPD to use mass aerial surveillance to track virtually all residents’ movements. Although Baltimore discontinued the program, it is far from the only city to employ such intrusive technologies. This decision is an important victory in protecting our Fourth Amendment rights and a big step toward ending intrusive aerial surveillance programs, once and for all.