What is the test for obtaining an affidavit for a search warrant based on an anonymous tip?

Federal courts also have stressed the importance of demonstrating the reliability of an anonymous tip in the context of an affidavit for a search warrant. For example, in United States v. Laws (D.C. Cir. 1986) 808 F.2d 92 (Laws), the federal appellate court explained: "An affidavit predicated upon an informant's tip has been regarded as vulnerable because the tip is hearsay, which like all hearsay, is susceptible to special concerns of perception and veracity. If the tip is to serve as a basis for a finding of probable cause, the 'neutral and detached magistrate' issuing the warrant must have substantial reason to believe that nonetheless the hearsay is reliable. Without that determination, the magistrate would cede his duty to gauge probable cause to the informant and the possibly overzealous law-enforcement officer." (Id. at pp. 94-95.) Probable cause may be based on "mutually-reinforcing" tips at least one of which was

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based on first-hand knowledge, and consistent behavior observed by police could support probable cause. (Id. at p. 103.)⁶