美国警方依据车牌识别摄像头判定的可疑行驶模式拦车
Police are pulling people over because license plate cameras say their travel patterns look "suspicious"
美国公民自由联盟（ACLU）梳理了多起警方仅凭 Flock 等自动车牌识别（ALPR）摄像头数据就拦停车辆的案例，最早可追溯到 2025 年。其中一名女子在跨州旅行时被自称 FBI 探员者查牌拦下，理由是她来自外州、行程与数据库记录不符；另一名男子则因往返威斯康星州与密歇根州被拦，警方怀疑其贩运大麻。今年一名俄克拉荷马州法官将此类拦停称为违宪的无差别大规模监控，佛州一名议员已提出要求搜查 ALPR 数据库须取得搜查令的法案。
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In context: Communities across the US have pushed back against the deployment of AI-powered automatic license plate readers (ALPRs) because of concerns about mass surveillance. Reports over the past year or so illustrate how authorities have used data from these devices to conduct traffic stops based on nothing more than "suspicious" travel patterns.
The ACLU recently outlined a pattern of police traffic stops based solely on data from Flock cameras and other license plate readers. The reports go back to at least 2025 and show how closely authorities can track the movements of most motorists.
In one case from late 2025, a woman only understood the extent of the surveillance when an officer demonstrated the software following a traffic stop. As she traveled through several states on a road trip to Florida, a self-identified FBI agent ran her license plate through a database and stopped her simply because she was from another state and her recent travels seemed unusual compared to the information the ALPR network had on her.
Although the account did not specifically mention Flock, the agent likely used a database built by Flock or another company that has installed ALPRs in thousands of communities nationwide. The AI-powered cameras automatically input passing cars' license plates (not always accurately) into nationwide databases that authorities can search without warrants.
The technology lets officers theoretically track the movements of any vehicle that has driven past ALPRs. In some cases, authorities can track associations between different vehicles and mobile devices to build and link profiles. While supporters claim the cameras can help solve crimes, find missing persons, and combat illicit trafficking, multiple incidents have raised concerns over police conduct.
Dozens of officers have been caught using the cameras to stalk ex-partners. Even in routine police work, traffic stops based on ALPR data raise questions about whether driving patterns amount to probable cause.
In another 2025 case, police stopped a man simply because he drove back and forth between his home in Wisconsin and Michigan. Because marijuana is legal in Michigan, authorities suspected that anyone driving in and out of the state might be trafficking it to parts of the country where it remains illegal.
Earlier this year, an Oklahoma judge called a similar stop unconstitutional indiscriminate mass surveillance, even though it led to the seizure of 91 pounds of meth. In response to such incidents, a Florida representative recently introduced a bill to require warrants to search ALPR databases. However, other politicians want to ban the technology outright.