In March 2024, New York City Mayor Eric Adams announced that the New York City Police Department (NYPD) would pilot electromagnetic gun detectors at various entrances to the city’s subway stations. Because all weapons are banned in the New York City transit system, it is safe to assume that discovery of any of them would result—at a minimum—in the screened individual being denied access to the subway. Although this policy raises serious concerns under the Second Amendment (which I discuss here), this post focuses on the Fourth Amendment implications of conditioning entrance to public transit on a search.
The NYPD’s draft impact and use policy discusses specific aspects of the policy. When the detectors are in use, the NYPD will post signs notifying the public prior to their entry to the monitoring area. Individuals who refuse to be screened must leave the station. Additionally, an individual may elect an alternative screening method, presumably a frisk. If the system detects a potential weapon on an individual, the detector will transmit an image of the individual along with a “cube” indicating the location of the potential weapon. The accompanying police officer can then search the area on the person’s body outlined by the cube.
The Fourth Amendment provides that “[t]he right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated.” Separately, the Amendment contains a requirement that law enforcement obtain search warrants “upon probable cause, supported by Oath or affirmation” before searching a person or their effects. There are, of course, certain exceptions to the warrant requirement, including what the U.S. Supreme Court has articulated as the “special needs” exception. One application of this exception is familiar: searches prior to boarding airplanes at commercial airports. The NYPD references the special needs doctrine in its statement announcing the gun detection program but fails to provide any support in case law or elsewhere as to why it applies to searches of passengers on the New York City subway.
This is not the first attempt by the NYPD to subject subway passengers to suspicionless searches. In 2005, after several terrorist attacks on public transportation in Madrid, Moscow and London, the NYPD commenced a “Container Inspection Program” designed to deter terrorists from carrying explosives on the New York City subway. Under this program, which is still in effect, the NYPD sets up variable checkpoints at certain subway entrances and randomly searches passengers’ backpacks and large containers. Several individuals challenged this program on Fourth Amendment grounds. In MacWade v. Kelly, the Second Circuit upheld the program on the basis that it fell within the special needs exception to the Fourth Amendment. After concluding as a threshold matter that prevention of a terrorist attack on the subway serves a special need, the court balanced several factors and concluded that the program was constitutional. Those factors, set out in different cases by the U.S. Supreme Court, are: (1) the weight and immediacy of the government interest, (2) the nature of the subject’s privacy interest, (3) the character of the intrusion imposed by the search, and (4) the efficacy of the search in advancing the government interest. The court held that although subway riders have a full expectation of privacy in their containers, the government interest was immediate and substantial, the search was minimally intrusive, and that its efficacy was supported by the testimony of two NYPD officers and a counter-terrorism expert.
Setting aside the merits of MacWade, the NYPD’s use of weapon detectors is significantly broader and more intrusive than searches solely to identify explosive devices in backpacks and large containers. First, the new searches are not limited to backpacks and large containers. If the electromagnetic detector flags an area on a person’s body, the NYPD will frisk that person, and it is unlikely that someone can elect to refuse the secondary search and leave once the detectors flag him or her.[1] Second, the detectors are being used to flag any weapon, not just explosive devices. Considering that all weapons, including pocketknives and pepper spray, are banned in the subway system, it is safe to assume that detection of any weapon would open the passenger to liability. And although the government’s interest in preventing terrorism may be sufficient to satisfy the special needs exception to the Fourth Amendment’s warrant requirement, the same cannot be said for garden variety crime prevention. Indeed, the Supreme Court struck down a highway checkpoint program whose primary purpose was to uncover illegal narcotics. Finally, under the large container policy, a rider who elects not to have their backpack or container searched can re-enter the subway system without the unsearched container. But because this new policy deals with the riders themselves rather than their possessions, the rider cannot merely re-enter the system. In fact, the NYPD does not say if the rider may ever again legally enter the system.
Considering that less than half of New Yorkers own automobiles and that many local politicians are openly hostile to vehicular travel, for many, public transportation may be the only practical mode of navigating the city. In effect, the search policy forces those without cars or funds to consistently spend on ride-share trips (which can easily cost over $50 each way between Manhattan and the outer boroughs) to sacrifice their Fourth Amendment rights simply to travel. If students don’t shed their constitutional rights at the schoolhouse gates, surely adults should not shed them to ride the subway.
[1] In an analogous context, courts have unanimously held that once a passenger submits to initial screening at an airport, he or she may not leave upon being flagged for secondary inspection. See United States v. Aukai, 497 F.3d 955, 960–61 (9th Cir. 2007) (en banc); United States v. Hartwell, 436 F.3d 174, 181 n.12 (3d Cir. 2006) (Alito, J.); United States v. Herzbrun, 723 F.2d 773, 776 (11th Cir. 1984); United States v. DeAngelo, 584 F.2d 46, 48 (4th Cir. 1978).