Aguilar v. State of Texas

In Aguilar v. State of Texas, 378 U.S. 108, 84 S.Ct. 1509, 12 L.Ed.2d 723 (1964), the Supreme Court held that for a search warrant to issue upon information supplied by an informer, the magistrate issuing the warrant must be informed (1) of some of the underlying circumstances from which the informant concluded that the evidence [in that case, as in this, narcotics] was where he claimed it was, and (2) of some of the underlying circumstances from which the police concluded that the informer was credible.