The fourth amendment prohibition of unreasonable searches and seizures pertains only to the actions of government officials or their agents. Material obtained by private citizens pursuing personal goals is not covered by the fourth amendment. Property obtained in such a search may subsequently be turned over to the government and used as evidence, so long as no government officials played a part in the search or in the acquisition of the evidence. The court cases reviewed focus on whether or not the private person involved, given all the circumstances, must be regarded as having acted as an instrument or agent of the police. The cases indicate that a person will be viewed by the courts as a "police agent" if the police instigate, encourage, or foster the search; if there is joint participation between private citizens and police officers; if the police have significantly involved themselves in the search; or if the police have preknowledge of the private person's expressed intent to conduct a search or seizure and acquiesce in its execution.