The authors hypothesized that laypersons would perceive reasonable consentors to be only those individuals who had a high degree of control over the place of search and a close social relationship with the subject of the search. The general perception of police detectives was anticipated to be somewhere between the lay and legal perception as expressed in the case law. In the experiment, two levels of third party control over the place of search were crossed with two levels of social relationship with the suspect. Both the students and the police detectives thought that third party consentors should have a high degree of both place control and social relationship to be deemed reasonable. The results showed that, in the absence of a strong motivation to conduct a warrantless search, police detectives' perceptions corresponded with those of lay persons. Unlike judicially crafted standards of reasonableness, the detectives felt that third parties with possessory control but no social relationship with the target of the search were unreasonable consentors. 2 tables and 31 references