Constitutional Concerns
The Fourth Amendment protects Americans against "unreasonable searches and seizures." Court decisions have imposed constitutional limits on some forms of prolonged location tracking, but the rules for ALPR databases remain contested.
In 2018, the Supreme Court ruled in Carpenter v. United States that accessing historical cell phone location data requires a warrant. Whether and when the same warrant rule applies to ALPR searches is being litigated and depends on the facts, length of tracking and jurisdiction. Many ALPR searches currently occur without a judicial warrant.
The Institute for Justice has filed a federal lawsuit against Norfolk, Virginia's Flock network, arguing it violates the Fourth Amendment. A federal judge ruled the case could proceed, noting that "a reasonable person could believe that society's expectations [of privacy] are being violated by the Norfolk Flock system."