Law and Human Behavior, Vol. 15, No. 2, 1991 Reasonable Expectation of Privacy Third-Party Consent Searches* and Dorothy K. Kagehiro,t Ralph B. Taylor,~ and Alan T. Harland$ Reasonable expectation of privacy is discussed in the context of searches conducted without the warrants usually required by the Fourth Amendment but with the consent of a third party, who is not the target of the search. Case law on this issue is neither consistent nor clear-cut. Psychological theory and research clarify this issue by establishing closer correspondence between legal concepts and assumptions and individuals' actual behaviors and social expectations. The key legal components of reasonable expectation of privacy are delineated, with regard to third-party consent: "common authority" areas versus "exclusive use" areas and the assumption of risk doctrine. Next, the psy- chological theory and research on interpersonal relations and human territorial functioning are re- viewed as they relate to the legal components of privacy regulation. Taken together, the legal criti- cisms of this warrant exception category, and possible discrepancies between the legal assumptions concerning interpersonal and territorial functioning among co-residents and the actual behaviors and expectations suggested by psychological theory and research, raise questions about its validity. This article discusses legal perceptions of reasonable expectation of privacy in third-party consent searches. We begin with a review of the legal assumptions concerning privacy expectations in third-party consent searches. In the next sec- tion, after considering some of the major court decisions concerning key compo- nents of reasonable expectation of privacy, we review the psychological theory and research on interpersonal relations and human territorial functioning as they * Portions of this article were presented in a symposium at the annual meeting of the American Psychological Association, New York City, August 1987. We thank Carol M. Wemer and two anonymous reviewers for their comments on an earlier draft. Requests for reprints and other cor- respondence should be sent to Dorothy Kagehiro, 1 Meridian Plaza, #930, Philadelphia, Pennsyl- vania 19102. Philadelphia, Pennsylvania. $ Department of Criminal Justice, Temple University. I21 0147-7307/91/0400-0121506.50/0 9 1991 Plenum Publishing Corporation