United States Supreme Court
Evidence discovered during an unlawful stop need not be suppressed where the connection between the unconstitutional conduct and the discovery of evidence is sufficiently attenuated by the intervening discovery of a valid arrest warrant.
Utah v. Strieff applied the attenuation doctrine to hold that evidence discovered incident to an arrest made pursuant to a preexisting valid arrest warrant need not be suppressed, even though the initial investigatory stop was unlawful.