Consider the following scenario: a person consents to giving some evidence to aid the investigation or prosecution of a criminal,with the reasonable, good-faith assumption that the use of that evidence will be limited in scope to the particular investigation/trial. That evidence is later used by prosecution against the person who provided the evidence in a separate, unrelated case.
One can easily imagine instances where this occurs:
- This question is inspired by the recent revelation of some police precincts of archiving DNA evidence collected in one investigation for use in later investigations. The policy in question allowed police to use DNA samples obtained during investigation of rape victims to archive the victim's DNA evidence in databases which were later searched and used to implicate the victims in unrelated crimes. This particular issue has been explored on this site here.
- A person surrenders dashcam footage to a police officer because it contains evidence of a hit and run accident. The footage is later used as evidence against the person because it shows that he or she was speeding earlier that day.
- Police solicit tips/evidence in the search for a suspect in a violent crime. A person gives an eyewitness account of the crime in a good-faith attempt to aid in the investigation. The eyewitness account implies that the person was in a location and time in violation of their parole, which is later used against them in a separate trial. (edit: I understand that the Exclusionary Rule doesn't generally apply to parole revocation hearings, but the sentiment is the same and one could easily modify the scenario to be about a different secondary crime).
What policies or statutes govern the use of evidence past its original intended use? Does consent to surrender evidence in once case amount to surrendering that evidence for all uses, forever? My prima facie assumption would be that the Exclusionary Rule would apply here because the evidence was obtained in a somewhat disingenuous / coercive manner (good-faith assumption that the evidence was only being provided to aid in investigation of a particular crime) and that such a bait-and-switch collection of evidence amounts to a violation of the 5th Amendment.