## Facts

- A detective received an anonymous tip about possible narcotics activity at a residence and conducted intermittent surveillance, observing short-term visitors consistent with suspected drug dealing.
- The detective saw Edward Strieff leave the residence and stopped him without reasonable suspicion.
- During the stop, the detective obtained Strieff’s identification and requested a warrant check.
- Dispatch reported an outstanding arrest warrant for a traffic-related violation.
- The detective arrested Strieff on the warrant and, in a search incident to arrest, found methamphetamine and drug paraphernalia.
- Strieff moved to suppress the evidence as the product of an unconstitutional stop under the Fourth Amendment.

## Issues

1. Whether the exclusionary rule requires suppression of evidence found in a search incident to arrest when the arrest stems from an outstanding warrant discovered only because of an unlawful investigatory stop.
2. Whether, under the attenuation doctrine, discovery of a valid, preexisting warrant is an intervening circumstance sufficient to break the causal link between the illegal stop and the evidence seized.

## Decision

- The Supreme Court reversed the Utah Supreme Court in a 5–3 decision.
- The Court held the evidence was admissible because the valid, preexisting arrest warrant was an intervening circumstance that attenuated the connection between the unlawful stop and the evidence.
- Applying the Brown v. Illinois factors:
  - Temporal proximity favored suppression because the search closely followed the unlawful stop.
  - Intervening circumstances favored admission because the warrant predated and was independent of the stop, and it required the officer to arrest Strieff once discovered.
  - Purpose and flagrancy favored admission because the officer’s misconduct was, at most, negligent rather than purposeful or flagrant.

## Legal Principles

- The exclusionary rule applies to both direct and derivative evidence obtained through unconstitutional searches or seizures, but it is limited where deterrence benefits are outweighed by social costs.
- Under the attenuation doctrine, evidence is admissible when the connection between unlawful police conduct and the evidence is sufficiently remote or interrupted by an intervening circumstance.
- Attenuation is assessed using the Brown factors: (1) temporal proximity, (2) intervening circumstances, and (3) purpose and flagrancy of the official misconduct.
- A valid, preexisting, untainted arrest warrant discovered after an unlawful stop can qualify as an intervening circumstance that breaks the causal chain, even though it is not the defendant’s voluntary act.

## Conclusion

The Court held that evidence found during a search incident to arrest on an outstanding warrant need not be suppressed even if the warrant was discovered through an unconstitutional stop, so long as the warrant and the nature of the officer’s conduct sufficiently attenuate the taint under Brown’s factors.


Utah v. Strieff, 579 U.S. 232 (2016)