A landmark Supreme Court ruling, **Chatrie v. United States**, which found that cell phone location history searches necessitate a warrant, is poised to create significant ripple effects across various surveillance technologies, particularly automated license plate readers (ALPRs). This decision, the first major Fourth Amendment case from the Supreme Court in eight years, directly addresses the core question of how law enforcement can utilize private data. It suggests that "geofence" searches, where police request location data for devices within a specified area during a crime, are protected by the Fourth Amendment, opening a critical debate on their future parameters. ### The Warrant Debate for ALPRs Should ALPR searches ultimately require a warrant, experts predict a radical transformation in how these extensive camera networks are deployed. **Flock Safety**, a dominant ALPR vendor, boasts between 90,000 to 100,000 cameras on public roadways, collecting an estimated 20 billion license plate records monthly. Police increasingly leverage this data for suspect identification. While the **Chatrie** case specifically involved **Google** providing geofence data, legal scholars highlight strong parallels with ALPR data. **Michael Soyfer**, an attorney at the **Institute for Justice**, pointed out that the Supreme Court expressed particular concern over the "retrospective and indiscriminate" nature of location history surveillance – descriptors equally applicable to ALPR data. **Soyfer** further noted that the ruling strengthens the case against ALPRs by emphasizing the global access police have to databases, rather than just isolated instances of access. "The justices drilled down on what was in the database and not just what police happened to access at a point in time," he stated. "The court's really emphasizing that it's looking at the capabilities of the technology overall rather than just what police did with it." Beyond ALPRs, the **Chatrie** decision could have broader implications for cases involving reverse keyword searches, cell tower dumps, and law enforcement's acquisition of commercial location data from brokers. ### Flock Safety's Stance In response, a spokesperson for **Flock Safety** asserted that the court's decision is not relevant to their operations. "The Supreme Court’s decision addresses geofence warrants for Google location history, which is categorically different from license plate recognition technology," the statement read. They argue that Google location history involves personal mobile device data, revealing continuous movements across both public and private spaces, whereas "Flock’s ALPR technology, by contrast, captures point-in-time images of vehicles in public view." **Flock Safety** maintains that courts have "repeatedly and uniformly" differentiated ALPRs from technologies like cell site location information and mobile geolocation data, and they do not believe this ruling undermines that settled precedent. They also cited a side note in the Supreme Court opinion that appears to differentiate Fourth Amendment search standards based on whether tracking occurs on "public roads." ### 'Indisputably Private' Information In the **Chatrie** case, the government contended that short-term location data collection did not warrant Fourth Amendment protections. However, the high court sided with Chatrie, asserting that the government was "wrong about the incapacity of short-term location information to reveal private matters." The opinion highlighted that even a few hours of location history could reveal visits to "indisputably private" locations such as a psychiatrist's office, an abortion clinic, an AIDS treatment center, a strip club, or a by-the-hour motel. "Location History enables police officers to focus on precisely those sites — to see, in a given time block, who shows up," the ruling stated. **Andrew Guthrie Ferguson**, a law professor at **George Washington University** and author of *Your Data Will Be Used Against You*, argues that the connection of license plates to law enforcement networks of personal data – revealing location, travel patterns, and residences – makes ALPR searches fundamentally similar to cell phone location history searches. "Modern ALPRs are just the connecting point to a much larger system of personally revealing information stored in police and connected public databases," **Ferguson** explained. These databases often integrate ALPR data with social media activity, surveillance video, body camera and drone footage, gunshot audio detection sensor data, and police dashboard camera recordings, enabling the creation of extraordinarily detailed dossiers on individuals. While acknowledging some differences due to license plates being designed for identification, **Ferguson** stressed, "I think it is a mistake to think about ALPRs standing alone." He concluded, "Chatrie certainly strengthens the Fourth Amendment case against the warrantless collection of ALPR data."