Is consent valid for a warrantless search?

A warrantless search is justified if consent is given by a third party who possessed "common authority" over the effects to be inspected. United States v. Yarbrough, 852 F.2d 1522, 1534 (9th Cir.), cert. denied, 488 U.S. 866 (1988). "Even if the consenting third party does not in fact possess actual authority to consent, a warrantless search may be justified when the authorities have reasonable grounds to believe the consentor has apparent authority to consent." Id. (emphasis in original); see also United States v. Guzman, 852 F.2d 1117, 1121 (9th Cir.1988) ("[c]onsent to search may be obtained from a third party with common authority over the premises, or with some sufficient relationship to the place or effects to be searched").