Criminal ProcedureThe “independent source doctrine” is one of the exceptions to the exclusionary rule.

Under the independent source doctrine, if the officers would have sought and obtained a warrant even without the information learned from the improper search, the exclusionary rule does not apply to the evidence seized pursuant to that warrant.

To apply the independent source doctrine, a court must find that (a) police would have sought the warrant absent the information they learned from the impermissible search, and (b) after taking out the impermissibly learned information from the search warrant affidavit, probable cause would still support the issuance of a warrant.

In Nix v. Williams, 467 U.S. 431, the United States Supreme Court explaining the reasoning behind the independent source doctrine as follows:

“[T]he interest of society in deterring unlawful police conduct and the public interest in having juries receive all probative evidence of a crime are properly balanced by putting the police in the same, not a worse, position that they would have been in if no police error or misconduct had occurred. . . . When the challenged evidence has an independent source, exclusion of such evidence would put the police in a worse position than they would have been in absent any error or violation.” Id. at 443.

The doctrine applies to evidence acquired not only through Fourth Amendment violations, but also through Fifth and Sixth Amendment violations.

Independent Source Doctrine vs. Inevitable Discovery Doctrine

Independent source doctrine is sometimes confused with the inevitable discovery doctrine, another exception to the exclusionary rule. But the two doctrines are different.

While the inevitable discovery doctrine applies if evidence would have been discovered absent the unlawful search, the independent sourcedoctrine applies when the evidence actually was obtained independently from activities untainted by the initial illegality.  Further, the two doctrines create different incentives – applying the inevitable discovery doctrine to warrantless searches would eliminate the warrant requirement, while applying the independent source ordinarily keeps officers from overreaching because in addition to the normal burden of convincing a magistrate that there is probable cause, the independent source doctrine adds the much more onerous burden of convincing a trial court that no information gained from the illegal entry affected either the law enforcement officers’ decision to seek a warrant or the magistrate’s decision to grant it.

Case Law Examples:

See: 

Murray v. United States, 487 U.S. 533 (1988).

See also:

United States v. Duran-Orozco, 192 F.3d 1277, 1281 (9th Cir. 1999): Agents tracked suspected drug smugglers to a house, looked through a window, and saw marijuana.  In the affidavit for the search warrant, the agent described the facts that led him to believe a search of the house would uncover evidence of drug smuggling, including the presence of marijuana.  This Ninth Circuit Court of Appeals held that the agents had conducted an impermissible search when they looked through the window. It nevertheless held that even without the information discovered from the impermissible search, the affidavit still would have provided probable cause for a search warrant.  It remanded the case to the district court to make a factual finding whether agents would in fact have sought a warrant had they not seen the marijuana.

United States v. Heckenkamp, 482 F.3d 1142, 1149 (9th Cir. 2007): When police conducted improper search and included tainted information in affidavit for subsequently obtained warrant, the Court excised the tainted information, examined the remaining information, and determined there was probable cause to support the subsequently obtained warrant.

United States v. Salas, 879 F.2d 530, 537 (9th Cir. 1989): Upholding district court’s determination that untainted portions of affidavit demonstrated probable cause, and describing defendant’s argument that “search warrant issued on an affidavit containing both tainted and untainted information cannot serve as an independent source” as “clearly contrary to the law of this circuit.”

United States v. Driver, 776 F.2d 807, 812 (9th Cir. 1985) (“The warrant may be upheld even where it contains tainted and untainted facts as long as the untainted portions contain a sufficient showing of probable cause to render the warrant valid.”).

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