What doctrine was outlined in Nix v. Williams regarding evidence?

The doctrine established in Nix v. Williams is centered around the principle of the inevitable discovery exception to the exclusionary rule. This rule permits the admission of evidence that, although initially obtained through potentially unlawful means, would have eventually been found through lawful investigation methods.

In the case, the court ruled that the evidence in question would have been discovered inevitably, even without the improper actions of law enforcement. This rests on the understanding that if law enforcement is able to demonstrate that the evidence would have been discovered through lawful means inevitably, regardless of the circumstances surrounding its collection, it can still be admitted in court. This doctrine balances the need to deter police misconduct with the practical reality that certain evidence can be found through routine investigative work without reliance on unlawful actions.