Most cops understand the importance of carrying a backup weapon. The primary could get lost, malfunction, or run out of ammo. It's wise not to put all of your survival eggs in one basket.
Given the complexity and uncertainty of the ever-changing Fourth Amendment rules, it's also wise not to put all of your search-and-seizure eggs in one basket. If you can identify two or more ways to justify a detention, arrest, search, or entry, you increase the odds that at least one of them will be upheld in court, and the contraband or evidence you found will be ruled admissible. This is where the "independent source" doctrine can help.
No Harm, No Foul
The rationale of the court-created exclusionary rule is that by suppressing evidence, courts will deter police from making unreasonable searches and seizures. But if a criminal defendant's rights have not been violated, there is no police misconduct to deter, so no suppression. And the defendant's rights are not violated if the search or seizure can be justified under at least one standard theory, even though another theory advanced by police or prosecutors does not support the action taken.
The U.S. Supreme Court has emphasized repeatedly that although one source of contested evidence might be "tainted," a different source may save the evidence from suppression.
- "If knowledge of the facts is gained from an independent source, they may be proved like any others." (Silverthorne Lumber v. U.S.)
- "The 'fruit of the poisonous tree' doctrine excludes evidence obtained from or as a consequence of lawless acts, not evidence obtained from an independent source." (Costello v. U.S.)
- "It is clear from our prior holdings that the exclusionary rule has no application where the Government learned of the evidence from an independent source." (Segura v. U.S.)
- "The independent source doctrine allows admission of evidence that has been discovered by means wholly independent of any constitutional violation." (Nix v. Williams)
- "The 'independent source' doctrine permits the introduction of evidence initially discovered during, or as a consequence of, an unlawful search, but later obtained independently from lawful activities untainted by the initial illegality." (Murray v. U.S.)
For example, suppose you have a search warrant to search a house. Before telling the resident about the warrant, you ask for consent to come in and search, and the resident agrees. You then tell him that you also have a warrant. You now have two independent sources for evidence that you find inside.
If a court later finds that the warrant was so defective that it was unreasonable to rely on it, you can invoke consent to justify the search. Or, if the court had found that the consent was not voluntary or was not given by someone who reasonably appeared to have authority to consent, the warrant would be an independent source of the evidence. To defeat the "independent source" doctrine, a defendant would have to attack the validity of each and every justification you claim.
Cell Phone Searches Today
Here's the perfect opportunity to apply the "independent source" doctrine when you search. Can you search a suspect's cell phone incident to his lawful arrest? It all depends on where you work.