When police conduct a search, the amendment requires that the warrant establish probable cause to believe that 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. [ 80 ] [ 81 ] 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", [ 82 ] reiterating Carroll ' s 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. [ 83 ] 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. [ 84 ] 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." [ 85 ] 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