Automated license plate readers (**ALPRs**) represent a significant expansion of mass surveillance. These systems continuously photograph passing cars, creating a vast, searchable database of where and when nearly everyone drives. While cities are urged to cease their use, for those that remain operational, legal and legislative safeguards are crucial to mitigate their inherent harms. At the forefront of these proposed safeguards is a mandatory warrant requirement for police to search stored **ALPR** data. This wouldn't legitimize mass surveillance, but it would introduce an essential judicial check, forcing law enforcement to justify searches to a judge before accessing highly personal movement records. Without this independent oversight, numerous instances of improper searches, many exposed by organizations like the **EFF**, have come to light, directly violating fundamental rights. ### The Imperative of a Warrant A warrant, under the **Fourth Amendment**, requires a judge to find probable cause and specificity. Many warrantless police searches of **ALPR** data demonstrably lack both. Instances of abuse range from profiling Romani people and monitoring protesters to investigating abortions, tracking immigrants for deportation, retaliating against critics, and even stalking romantic partners, sometimes with no stated reason beyond a casual “LMAO.” A warrant requirement would compel law enforcement to justify these searches *before* accessing sensitive location records, rather than leaving individuals to discover and challenge abuses after the fact. Warrants serve as a critical check on police power. Before officers can search an individual or their property, they must convince a neutral judge, under oath, that probable cause exists – meaning a fair probability that the search will yield evidence of a crime. The warrant must also describe with particularity what will be searched, preventing fishing expeditions. Crucially, the officer seeking the search is not the one who determines its justification. This principle underpins warrant requirements for various forms of police surveillance, including wiretapping phone calls, searching cell phone contents, and obtaining historical cell phone location records. Given that stored **ALPR** data reveals intimate details about our lives – where we go, when, and with whom – a warrant requirement for police searches of this data is equally essential. A federal judge in Oklahoma recently affirmed this position. ### The Perils of Warrantless Access: San Jose, California San Jose offers a stark illustration of the dangers of allowing law enforcement to search stored **ALPR** data without a warrant. The **EFF** and the **ACLU of Northern California**, representing **SIREN** and **CAIR-California**, are currently challenging this practice in a lawsuit. The sheer volume of searches conducted by the **San Jose Police Department (SJPD)** underscores the issue: 261,711 searches between June 5, 2024, and June 17, 2025, averaging approximately 692 searches per day. This scale is a direct consequence of the absence of a warrant requirement, which would significantly curtail such casual surveillance. Inevitably, unchecked power leads to abuse. In September, San Jose's police chief disclosed the firing of an officer who used the department's **ALPR** system to track a woman who had accused his cousin of domestic violence, subsequently sharing her location information with the cousin. This abusive search only came to light when the woman reported that her alleged assailant had implied he was tracking her. A warrant requirement would have prevented this breach. Similar problems are evident nationwide. Consider how each of the following scenarios might have unfolded differently had officers been required to submit a sworn warrant application to a judge. ### Documented Abuses of ALPR Data #### Racial Profiling of Romani People Over 80 law enforcement agencies have searched the **Flock** network using terms that unfairly stereotype Romani people, often without any mention of a crime. For instance, the **Grand Prairie (Texas) Police Department** conducted six searches for “g*psy” using a **Flock** feature that identifies vehicles traveling together, effectively targeting an entire community based on ethnicity rather than criminal activity. No judge should authorize such a warrant. Ethnicity is not evidence of a crime, and a search targeting an entire ethnic group is the antithesis of particularity. #### Surveillance of Protesters In 2025, the **EFF** documented over 50 agencies conducting hundreds of protest-related searches of **ALPR** data. The **Tempe (Arizona) Police Department**, for example, ran three searches linked to the **No Kings** protest across 425 networks, again without identifying any specific crime. Such actions lack probable cause and target activities protected by the **First Amendment**. #### Investigating an Abortion In 2025, a Texas sheriff’s office searched over 83,000 **Flock** cameras, including those in Washington and Illinois where abortion is legal, citing the reason as “had an abortion, search for female.” Records later obtained by the **EFF** revealed deputies had initiated a “death investigation” after the woman’s partner, subsequently charged with assaulting her, reported her self-managed abortion. In a state where abortion is legal, a judge would not grant a warrant for such a search. #### Finding Immigrants for Deportation San Francisco police have allowed out-of-state agencies to search the city’s **ALPR** data, a practice that violates **California law**. At least 19 of these searches were marked as related to **ICE**, despite San Francisco being a sanctuary city. This issue is widespread, with one investigation uncovering over 4,000 instances where police departments nationwide searched stored **ALPR** data on behalf of federal law enforcement, including for immigration investigations. Some agencies even link their **ALPR** systems to an “Immigration Violator” hotlist populated by **ICE**, which includes plates tied to administrative warrants issued by **ICE** agents without judicial oversight. Similarly, a judge in a state where police are prohibited from enforcing immigration law would not issue a warrant for these types of searches. #### Retaliation Against a Critic In May 2025, Navy veteran **Napoleon Jones** lawfully recorded a police traffic stop in Sussex, Wisconsin. Jones alleges that a **Waukesha County** deputy retaliated by stopping and arresting him. He was released five hours later without citations or charges, and the deputy’s supervisor concluded the stop was illegal. Jones filed a complaint against the deputy the following day. In the subsequent weeks, officers reportedly conducted over 100 **Flock** searches against Jones, some initiated by the very deputy he had complained about. Deputies testified that a lieutenant ordered these searches in connection with Jones’s complaint. No judge should authorize tracking an individual for criticizing the police. #### Stalking Romantic Partners The **Institute for Justice (IJ)** has documented multiple cases where officers have used **ALPR** data to stalk romantic partners, highlighting a disturbing pattern of personal misuse of these powerful surveillance tools.