This is a follow-up to my blog entry of May 7, 2008, ("Practical Obscurity and Public Records") in which I discussed the doctrine of practical obscurity as it relates to online public records. In this blog, we will examine how rapidly advancing technology is further eroding privacy by removing even more barriers to practical obscurity in real time.
Once upon a time, if you wanted to know where a particular car or person had been going, you had to station yourself on a street corner, follow them or their vehicle yourself, or else hire a PI to track that individual's movements. The information was public in the purest sense: anyone could tail the person, but the time, effort and money required made doing so impractical. Only someone with the real motivation, time and resources to invest would bother. Suddenly, the ubiquity of networked automated license plate recognition systems, such as those marketed by Flock Safety and similar vendors, has made that all too easy.
Today, fixed and mobile cameras continuously photograph plates, vehicle descriptions, locations, and timestamps, then feed the results into searchable cloud databases that span thousands of jurisdictions. With a few simple keystrokes an agency can reconstruct recent movements, associations, and patterns: work, medical visits, places of worship, clinics, protests, without ever leaving the office. What was once a fleeting public observation has become a running historical log.
The same pattern of harm we saw with online public records has reappeared. Just as fraudsters once copied signatures and notary seals from digitized deeds, individuals with access to these systems have used plate queries for personal stalking of partners or former partners. Just as identity thieves harvested Social Security numbers and addresses from court databases, the networks have been employed to track people across jurisdictional lines for purposes ranging from abortion investigations to immigration enforcement and protest monitoring. Security lapses have left cameras streaming live video and archives without proper authentication; outdated software and physical access have yielded root control. False plate reads have even prompted armed stops of innocent drivers. In each case the technology lowers the cost and effort of obtaining sensitive information about people who are not the targets of any legitimate investigation.
A single plate sighting on a public road remains as public as a deed sitting in an old canvas book on a dusty courthouse shelf. Yet the continuous aggregation of those sightings produces the modern equivalent of the narrative report or abstract that the real-estate attorney in my prior blog described years ago: individual public facts assembled into an intimate private profile. As we saw in the Supreme Court's decision in U.S. Department of Justice v. Reporters Committee for Freedom of the Press, 489 US 749 (1989), although arrest records were available at local courthouses, the computerized compilation of “rap sheets” invaded privacy precisely because it destroyed their practical obscurity. That same principle applies when movement data that once required real-time physical presence is transformed into a searchable national diary.
The Court later applied similar reasoning to digital location tracking in Carpenter v. United States, 585 U.S. 296 (2018). There the government obtained months of historical cell-site location information, records generated automatically whenever a cell phone connected to nearby towers, (without a warrant), relying instead on a lower standard under the Stored Communications Act (18 U.S.C. §§ 2701-2712). The Court held that accessing this detailed, retrospective chronicle of a person’s movements constitutes a Fourth Amendment search requiring a warrant supported by probable cause. Individuals maintain a legitimate expectation of privacy in the whole of their physical movements, the Court explained, and the unique depth, breadth, and automatic nature of the data prevent the third-party doctrine from extinguishing that interest. The parallel is clear: whether the government compiles scattered courthouse records into a comprehensive dossier or networks cameras and cell towers to reconstruct where people have been, technology can erase the practical barriers that once kept such information obscure, and the privacy interest does not simply disappear.
There are differences in scale and character. Land and court records are snapshots in time of events past; these camera networks generate a continuous record of location that can be queried retrospectively. The primary users are law-enforcement agencies rather than private citizens, though private-party access and employee misuse still occur. Single plate reads continue to be treated as ordinary public-view observations; it is the network-scale reconstruction that raises the deeper question, much as the prolonged historical tracking did in Carpenter.
Some jurisdictions have already begun to respond. Dozens of municipalities have terminated or suspended contracts after audits revealed unauthorized sharing or policy violations. State legislatures are tightening retention periods, restricting out-of-jurisdiction and federal access, and in some instances requiring warrants or limiting use to serious crimes. Public pushback, transparency tools that allow individuals to check whether their plates were queried, and even physical removal of cameras reflect the same citizen expectation voiced nearly two decades ago.
The use (and misuse) of this technology is government overreach at its worst. Taxpaying citizens have the right to expect that their elected officials will take positive steps to protect privacy once the old practical-obscurity barriers have been erased by technology. The doctrine itself has never been codified as a formal legal right, but rather a de-facto protection arising from cost and inconvenience. When that cost collapses, whether by putting deeds online, networking cameras that log every vehicle movement, or compiling cell-site records into a detailed history of where someone has been, the privacy interest does not disappear. It simply requires deliberate replacement through redaction rules, access controls, retention limits, audit logs, contractual restrictions, and clear legislative boundaries. The problem has expanded from static records about property and past court events to continuous records of where people go in the present. The conceptual language remains the same; the policy task is to rebuild the friction that technology has removed.