Evidence obtained after the arrest may not apply retroactively to justify the arrest. When police conduct a search, the amendment requires that the warrant establish probable cause to believe the search will uncover criminal activity or contraband. They must have legally sufficient reasons to believe a search is necessary. In Carroll v. United States (1925), the Supreme Court stated that probable cause to search is a flexible, common-sense standard. To that end, the Court ruled in Dumbra v. United States (1925) that the term probable cause means "less than evidence that would justify condemnation," reiterating Carrolls assertion that it merely requires that the facts available to the officer would "warrant a man of reasonable caution" in the belief that specific items may be contraband or stolen property or useful as evidence of a crime. It does not demand any showing that such a belief be correct or more likely true than false. A "practical, non-technical" probability that incriminating evidence is involved is all that is required. In Illinois v. Gates (1983), the Court ruled that the reliability of an informant is to be determined based on the "totality of the circumstances." Exceptions to the warrant requirement Consent If a party gives consent to a search, a warrant is not required. There are exceptions and complications to the rule, including the scope of the consent given, whether the consent is voluntarily given, and whether an individual has the right to consent to a search of another's property. In Schneckloth v. Bustamonte (1973), the Court ruled that a consent search is still valid even if the police do not inform a suspect of his right to refuse the search. This contrasts with Fifth Amendment rights, which cannot be relinquished without an explicit Miranda warning from police. The Court stated in United States v. Matlock (1974) that a third party co-occupant could give consent for a search without violating a suspect's Fourth Amendment rights. However, in Georgia v. Randolph (2006), the Supreme Court ruled that when two co-occupants are both present, one consenting and the other rejecting the search of a shared residence, the police may not make a search of that residence within the consent exception to the warrant requirement. Per the Court's ruling in Illinois v. Rodriguez (1990), a consent search is still considered valid if police accept in good faith the consent of an "apparent authority," even if that party