EFF Urges Federal Court to Mandate Warrants for ALPR Searches

Retroactive tracking meets the Fourth Amendment

Privacy groups argue that querying automated license plate reader networks constitutes a constitutional search requiring judicial oversight.

The legal challenge stems from United States v. Sturdivant, a case involving robbery investigations across Cleveland, Ohio. Police obtained surveillance footage showing the make, model, and color of a getaway vehicle, but lacked a license plate number. Rather than securing a judicial warrant, investigators executed broad queries across two commercial license plate reader networks: Flock Safety and ELSAG.

The database searches matched a vehicle registered to the defendant near the crime scenes, leading directly to an arrest. When defense attorneys sought to suppress the tracking data, a federal district court ruled against them. The judge determined that drivers have no reasonable expectation of privacy regarding license plates displayed in public spaces.

Civil liberties groups contest that logic directly. In their joint filing to the Sixth Circuit, the EFF and ACLU argue that querying billions of recorded plate locations cannot be equated to an officer spotting a car at an intersection.

Why commercial plate networks change the legal baseline

Automated license plate readers do not just snap isolated photos; they pool timestamps, GPS coordinates, and vehicle images into searchable commercial ecosystems. Combined databases from vendors like Flock and ELSAG allow investigators to run reverse lookups on travel patterns across entire regions over weeks or months.

The filing describes the infrastructure as a virtual time machine that reconstructs historical travel routes with a few keystrokes. In recent months, federal judges have begun questioning whether sweeping databases violate constitutional protections against general searches, with at least one district court labeling the systems an indiscriminate mass surveillance tool.

Similar friction between pervasive digital logging and consumer privacy has triggered disputes elsewhere, such as when LG faced court action over smart TV data collection, highlighting how invisible background monitoring increasingly clashes with statutory rights.

What it means for US drivers

The Sixth Circuit's pending decision will govern federal prosecutions across Kentucky, Michigan, Ohio, and Tennessee, but its influence could reach further. A ruling requiring probable cause warrants would force police departments using networks like Flock to adjust their daily investigative playbook.

If the appeals court creates a circuit split with other federal jurisdictions that permit open-ended ALPR queries, the question of whether police need a warrant to track vehicles retrospectively will likely head to the US Supreme Court.

The Sixth Circuit now faces a pivotal decision on electronic tracking. By determining whether querying private license plate networks counts as a Fourth Amendment search, the court will define just how freely law enforcement can sift through the digital exhaust of daily road travel.