The Exclusionary Rule, Standing, and Fruit of the Poisonous Tree

The exclusionary rule (Mapp v. Ohio applied it to the states) bars the government from introducing, in its case-in-chief, evidence obtained in violation of the Fourth, Fifth, or Sixth Amendments. The Supreme Court has repeatedly emphasized that the rule is a prudential deterrent remedy, not a personal right of the defendant, so it applies only where its deterrence benefits outweigh its substantial social costs. Exclusion reaches not only the direct product of the illegality (the 'tree') but also evidence derived from it (the 'fruit'), under Wong Sun v. United States.

If an illegal search reveals a key that leads to a locker that holds a confession, all of it may be suppressed as fruit.

However, the prosecution can break the causal chain and admit derivative evidence by establishing one of three doctrines: (1) independent source — the evidence was also discovered through a lawful source untainted by the illegality (Segura/Murray); (2) inevitable discovery — the evidence would inevitably have been found by lawful means (Nix v. Williams);

and (3) attenuation — the connection between the illegality and the evidence has become so attenuated that the taint is dissipated, judged by the time elapsed, intervening events (such as a defendant's voluntary act or an outstanding valid arrest warrant in Utah v. Strieff), and the flagrancy of the misconduct.

Fourth Amendment rights are personal and cannot be asserted vicariously. To move to suppress, the defendant must show that the challenged search or seizure violated his own reasonable expectation of privacy — a requirement the Court analyzes as part of the merits but which functions as 'standing' (Rakas v. Illinois). A passenger in a car generally has no expectation of privacy in the glove compartment or trunk and thus cannot challenge a search of those areas, though a passenger is seized during a traffic stop and may challenge the stop itself (Brendlin).

An overnight guest in a home has a legitimate expectation of privacy in the host's home (Minnesota v. Olson), but a person merely present for a short commercial transaction does not (Minnesota v. Carter). Ownership or possession of the seized property is relevant but not dispositive; the inquiry focuses on the defendant's connection to the place searched. The practical lesson for essays: before discussing whether a search was unlawful, confirm the defendant has standing to complain, because a defendant cannot suppress evidence obtained by violating a third party's rights even if the police acted illegally.

Even where a violation and standing exist, several doctrines admit the evidence. The good-faith exception (Leon) admits evidence seized in objectively reasonable reliance on a defective warrant; Herring v. United States and Davis v. United States extend good faith to reasonable reliance on negligent police recordkeeping and on binding appellate precedent later overruled, because exclusion deters deliberate or reckless misconduct, not isolated negligence.

Illegally obtained evidence may be used to impeach the defendant's own testimony on direct or cross-examination (Harris v. New York), though not to impeach other defense witnesses, and an involuntary (coerced) confession may never be used even for impeachment. Knock-and-announce violations do not trigger exclusion (Hudson v. Michigan). The exclusionary rule generally does not apply in grand jury proceedings, civil cases, parole/probation revocation hearings, or to bar an in-court identification. A live-witness identity discovered through an illegal search is rarely suppressed.

Finally, a Miranda violation (a Fifth Amendment prophylactic) does not automatically require suppression of the physical fruits of an un-Mirandized but voluntary statement (United States v. Patane), an important distinction from Fourth Amendment fruits.

The fruit-of-the-poisonous-tree analysis differs depending on which right was violated, a distinction that controls many close questions. For a Fourth Amendment violation, derivative physical and verbal evidence is presumptively suppressed unless one of the three taint-purging doctrines applies.

For a Fifth Amendment Miranda violation (a mere prophylactic, not a constitutional violation in itself), the fruits doctrine is far weaker: the physical fruits of a voluntary but un-Mirandized statement are admissible (United States v. Patane), a second statement given after proper warnings can be admissible even if a first un-warned statement preceded it (Oregon v. Elstad), and only a deliberate two-step 'question-first' strategy designed to circumvent Miranda triggers suppression (Missouri v. Seibert).

By contrast, a confession that is actually involuntary (coerced in violation of due process) is inadmissible for all purposes, including impeachment, and its fruits are suppressible. The attenuation doctrine is applied through three Brown v. Illinois factors plus flagrancy: the temporal proximity between the illegality and the evidence, the presence of intervening circumstances, and the purpose and flagrancy of the official misconduct.

In Utah v. Strieff, the discovery of a valid, pre-existing arrest warrant after an unlawful stop was a sufficient intervening circumstance to attenuate the taint of evidence found in the subsequent search incident to arrest, because the misconduct was negligent rather than flagrant. A voluntary, intervening act of free will by the defendant (such as voluntarily returning to confess days later, as in Wong Sun) also attenuates.

The independent-source and inevitable-discovery doctrines are distinct: independent source requires that the evidence actually was obtained through a genuinely separate, lawful channel, while inevitable discovery requires proof by a preponderance that lawful investigative means would inevitably have led to the same evidence (Nix v. Williams, the body-recovery case).

California's exclusionary remedy is governed by Proposition 8 (1982), whose 'Truth-in-Evidence' provision generally requires California courts to admit all relevant evidence except as required by the federal Constitution; the practical effect is that California suppresses evidence only when the United States Constitution compels it, so the federal good-faith and attenuation limits apply in full and there is no independent, broader California statutory exclusionary rule for most search-and-seizure violations.

Work a synthesis hypothetical: police unlawfully stop D without reasonable suspicion, discover during the stop that D has an outstanding valid arrest warrant, arrest him on the warrant, and find drugs in a search incident to that arrest. Under Strieff the warrant is an intervening circumstance that attenuates the taint, and because the unlawful stop was a good-faith mistake rather than flagrant misconduct, the drugs are admissible. Change the facts so the officer fabricated the basis for the stop in bad faith, and the flagrancy factor tips toward suppression.

The essay method: first establish a constitutional violation and the defendant's standing to assert it; second, identify the primary evidence and any derivative fruit; third, run independent source, inevitable discovery, and attenuation in turn; and fourth, check the catalog of exceptions — good faith, impeachment, knock-and-announce, grand jury, and the Miranda-fruits rules — that admit evidence despite a violation.

Purging the Taint and Key Exceptions