The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.
Fourth Amendment rights, like other constitutional rights, may be waived, and one may consent to a search of his person or premises by officers who have not complied with the Amendment.1 The Court, however, has insisted that the burden is on the prosecution to prove the voluntariness of the consent2 and awareness of the right of choice.3 Reviewing courts must determine on the basis of the totality of the circumstances whether consent has been freely given or has been coerced. Actual knowledge of the right to refuse consent is not essential for a search to be found voluntary, and police therefore are not required to inform a person of his rights, as through a Fourth Amendment version of Miranda warnings.4 But consent will not be regarded as voluntary when the officer asserts his official status and claim of right and the occupant yields because of these factors.5 When consent is obtained through the deception of an undercover officer or an informer's gaining admission without advising a suspect who he is, the Court has held that the suspect has simply assumed the risk that an invitee would betray him, and evidence obtained through the deception is admissible.6 Moreover, while the Court has appeared to endorse implied consent laws that view individuals who engage in certain regulated activities as having implicitly agreed to certain searches related to that activity and the enforcement of such laws through civil penalties,7 the implied consent doctrine does not extend so far as to deem individuals to have impliedly consented to a search on
pain of committing a criminal offense.8
Additional issues arise in determining the validity of consent to search when consent is given not by the suspect, but by a third party. In the earlier cases, third-party consent was deemed sufficient if that party
possessed common authority over or other sufficient relationship to the premises or effects sought to be inspected.9 Now, however, actual common authority over the premises is not required; it is sufficient if the searching officer had a reasonable but mistaken belief that the third party had common authority and could consent to the search.10 If, however, one occupant consents to a search of shared premises, but a physically present co-occupant expressly objects to the search, the search is unreasonable.11 Common social expectations inform the analysis. A person at the threshold of a residence could not confidently conclude he was welcome to enter over the express objection of a present co-tenant. Expectations may change, however, if the objecting co-tenant leaves, or is removed from, the premises with no prospect of imminent return.12