In Nix v. Williams, the Supreme Court created an "inevitable discovery" exception to the exclusionary rule. This exception allows the prosecution to introduce illegally obtained evidence at trial upon a showing that such evidence would inevitably have been obtained, even without the police misconduct. The Supreme Court rejected the imposition of a second prong on the inevitable discovery exception which would have required the government to prove the absence of bad faith. The purpose of the inevitable discovery exception is to prevent the "setting aside [of] convictions that would have been obtained without police misconduct."
Edward M. Macon,
Nix v. Williams: The Inevitable Discovery Exception to the Exclusionary Rule,
U. Rich. L. Rev.
Available at: http://scholarship.richmond.edu/lawreview/vol19/iss2/9