tainted evidence

In criminal law, tainted evidence, also called evidence of taint, is evidence obtained by unlawful means, such as a search conducted without a valid warrant. Because of its implications under the Fourth Amendment and the exclusionary rule, tainted evidence is generally inadmissible, and a conviction based solely on such evidence will be overturned.

Courts, however, recognize several exceptions to the exclusionary rule that permit the admission of tainted evidence:

Good-faith exception: Evidence may be admitted if officers reasonably relied on a warrant, statute, or binding precedent that was later found to be invalid.
- See Arizona v. Evans, 514 U.S. 1 (1995); Davis v. United States, 564 U.S. 229 (2011); Illinois v. Krull, 480 U.S. 340 (1987); Herring v. United States, 555 U.S. 135 (2009).
Independent source doctrine: Evidence initially discovered unlawfully may be admitted if later obtained through a constitutionally valid search.
- See Murray v. United States, 487 U.S. 533 (1988).
Inevitable discovery rule: Evidence unlawfully obtained is admissible if it would inevitably have been discovered by lawful means through an independent investigation.
- See Nix v. Williams, 467 U.S. 431 (1984).
Attenuation doctrine: Evidence may be admitted when the connection between the unlawful conduct and the discovery of the evidence is too remote, considering temporal proximity, intervening circumstances, and the flagrancy of misconduct.
- See Brown v. Illinois, 422 U.S. 590 (1975); Utah v. Strieff, 579 U.S. 232 (2016).
Impeachment exception: Tainted evidence may be used to impeach a defendant’s testimony, though not to prove guilt.
- See Harris v. New York, 401 U.S. 222 (1971).

The harmless error doctrine is not an exclusionary rule exception but a principle of appellate review. If tainted evidence was admitted, an appellate court may still uphold the conviction if the government proves beyond a reasonable doubt that the error did not affect the outcome. In Chapman v. California, 386 U.S. 18 (1967), the Court held that a reviewing court must declare beyond a reasonable doubt that the error did not contribute to the conviction. Courts consider the importance of the tainted evidence, whether it was cumulative of other testimony, and the overall strength of the prosecution’s case. State courts apply the same principle; for example, in Murray v. Gray, 982 So. 2d 1276 (Miss. Ct. App. 2008), the Court upheld a conviction where the weight of the evidence outweighed the harm from the error.

[Last reviewed in September of 2025 by the Wex Definitions Team]

Wex