D regularly enters employers' worksites to determine whether any illegal aliens may be present as employees. Acting pursuant to two warrants, D conducted a survey of the workforce at Davis Pleating in search of illegal aliens. The warrants were issued on a showing of probable cause by the INS that numerous illegal aliens were employed there, although neither of the search warrants identified any particular illegal aliens by name. A third factory survey was conducted at Mr. Pleat, another garment factory. Several agents positioned themselves near the buildings' exits, while other agents dispersed throughout the factory to question most, but not all, employees at their workstations. The agents displayed badges, carried walkie-talkies, and were armed, but no weapons were ever drawn. Agents approached employees and, after identifying themselves, asked them from one to three questions relating to their citizenship. If the employee gave a credible reply the questioning ended, and the agent moved on to another employee. If the employee gave an unsatisfactory response or admitted that he was an alien, the employee was asked to produce his immigration papers. Those employees not being questioned continued with their work and were free to walk around within the factory. Ps sued D challenging the constitutionality of INS factory surveys and seeking declaratory and injunctive relief. Ps claimed the factory surveys violated their Fourth Amendment right to be free from unreasonable searches or seizures and the equal protection component of the Due Process Clause of the Fifth Amendment. The court denied class certification and dismissed the union from the action for lack of standing, It then ruled that Ps had no reasonable expectation of privacy in their workplaces which conferred standing on them to challenge entry by the INS pursuant to a warrant or owner's consent. Reasoning from Terry v. Ohio that law enforcement officers may ask questions of anyone, it ruled that no P had been detained under the Fourth Amendment. The Court of Appeals reversed. concluding that the entire work forces were seized for the duration of each survey, which lasted from one to two hours because the stationing of agents at the doors to the buildings meant that 'a reasonable worker 'would have believed that he was not free to leave.'' It held that individual employees could be questioned only on the basis of a reasonable suspicion that a particular employee being questioned was an alien illegally in the country. D appealed.