What is the common law privilege against disclosure of the identity of a confidential informant?

Evidence Code section 1041 codifies the common law privilege against disclosure of the identity of a confidential informant. (See People v. Galland (2008) 45 Cal.4th 354, 363.) Evidence Code section 1042, subdivision (b), provides that disclosure of an informant's identity is not required to establish the legality of a search pursuant to a warrant or the admissibility of evidence obtained as a result of that search. A corollary rule provides, "'[I]f disclosure of the contents of [the informant's] statement would tend to disclose the identity of the informer, the communication itself should come within the privilege.'" (People v. Hobbs (1994) 7 Cal.4th 948, 961-962 (Hobbs).) "These codified privileges and decisional rules together comprise an exception to the statutory requirement that the contents of a search warrant, including any supporting affidavits setting forth the facts establishing probable cause for the search, become a public record once the warrant is executed." (Id. at p. 962.) Instead, a court may seal those portions of the search warrant affidavit that relate information that, if disclosed in the public portion of the affidavit, would reveal or tend to reveal a confidential informant's identity. (Galland, at p. 364; Hobbs, at p. 963.)

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