- Court
- U.S. Court of Appeals for the Fourth Circuit (en banc)
- Decided
- Citation
- No. 20-1495 (4th Cir. 2021) (en banc)
- Docket
- No. 20-1495
- Binding in
- Fourth Circuit (MD, VA, WV, NC, SC)
- Status
- Held
What the court held, in plain English
Because Baltimore’s aerial surveillance program enabled police to deduce information from the whole of people’s movements, accessing its data was a Fourth Amendment search, and operating it without a warrant violated the Fourth Amendment. The case involved planes, not license plate readers.
The question
Was the Baltimore Police Department’s Aerial Investigation Research (AIR) program, which photographed much of the city from planes during daylight hours, a Fourth Amendment search?
The facts
Under the AIR program, planes flying over Baltimore captured images of about 32 square miles of the city. Contractors used the images to track people and vehicles to and from the scenes of serious crimes, and prepared reports for police that could include the movements of people present at a scene before and after the crime. The program’s contract listed license plate readers among the police systems to be integrated with the aerial data.
Community groups and residents sued to stop the program and moved for a preliminary injunction, which the district court denied. A three-judge panel affirmed, and the full Fourth Circuit reheard the case.
What the court held
In an opinion by Chief Judge Gregory, the en banc court reversed and remanded: “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.” The court also held the appeal was not moot, because police retained data connected to investigations.
Judges Wilkinson, Niemeyer and Diaz wrote dissenting opinions.
Why it matters for license plate readers
Leaders is a federal appellate application of the aggregation reasoning from the Jones concurrences and Carpenter to surveillance of public spaces. It contrasts with McCarthy, where four ALPR cameras weren’t enough. Together they show the question courts ask: does the system, as actually used, reveal the whole of a person’s movements? See the mosaic theory.
What it didn’t decide
- Anything directly about license plate readers. The program used aircraft imagery.
- Anything binding outside the Fourth Circuit.
- A final judgment on the merits. The ruling came on a preliminary injunction appeal.
Later history
The court reversed the denial of the preliminary injunction and remanded the case to the district court. Baltimore had already ended the program after its pilot period. We have not traced every later proceeding, and we don’t have access to a commercial citator.
One ruling doesn’t settle every case. A decision binds courts within its jurisdiction, and outcomes depend on the facts. See how we summarize cases in our editorial standards.