In U.S. law, the principle that evidence seized by police in violation of the constitutional protection against unreasonable search and seizure may not be used against a criminal defendant at trial. The Supreme Court of the United States established the validity of the rule in Weeks v. U.S. (1914). In Wolf v. Colorado (1949) the court limited application of the rule to the federal courts; this decision was overturned in Mapp v. Ohio (1961), which required the rule to be applied universally. In the 1980s the court allowed an exception to the rule, holding that evidence obtained “in good faith” with a search warrant later ruled invalid is admissible.
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The exclusionary rule is designed to provide a remedy and disincentive, short of criminal prosecution, for prosecutors and police who illegally gather evidence in violation of the Fourth and Fifth Amendments in the Bill of Rights, which provide for protection from unreasonable searches and seizure and compelled self-incrimination. The exclusionary rule also applies to violations of the Sixth Amendment, which guarantees the right to counsel.
The exclusionary rule judges the admissibility of evidence based on deontological ethics; that is, it is concerned with how evidence is acquired, rather than what the evidence proves. For this reason, in strict cases, when an illegal action is used by police/prosecution to gain any incriminating result, all evidence whose recovery stemmed from the illegal action—this evidence is known as "fruit of the poisonous tree"—can be thrown out from a jury (or be grounds for a mistrial if too much information has been irrevocably revealed).
The exclusionary rule applies to all persons within the United States regardless of whether they are citizens, immigrants (legal or illegal), or visitors.
Before the strong version of the exclusionary rule was addressed and adopted by the federal courts, it had already been adopted by at least one state court, namely the Iowa Supreme Court:
The genesis of Iowa’s exclusionary rule was a civil case, Reifsnyder v. Lee, 44 Iowa 101 (1876).... The first application of the exclusionary rule in a criminal context occurred in the Height case, decided in 1902. Height involved a physical exam of the defendant against his will. 117 Iowa at 652, 91 N.W. at 935. This court held that the examination of the defendant violated the due process clause of the Iowa Constitution, as well as article 1, section 8’s prohibition of unreasonable searches. Id. at 661, 91 N.W. at 938.
In the 1886 case of Boyd v. United States, the U.S. Supreme Court addressed compulsory production of business papers, rather than an actual search and seizure, and the Court excluded those papers based on a combination of the Fourth and Fifth Amendments. Boyd was closely limited to its facts, and the Court stated in 1904 that the Fourth Amendment does not extend to "excluding testimony which has been obtained" by wrongful searches and seizures.
The strong version of the exclusionary rule was announced by the federal courts in 1914 in the case of Weeks v. United States., where it was found to be a requirement under the Fourth Amendment prohibiting unreasonable searches and seizures. This decision, however, created the rule only on the federal level. The "Weeks Rule", which made an exception for cases at the state level, was adopted by numerous states at a time during prohibition. In adopting the rule, actions by states often reflected attitudes towards prohibition, which was enacted by the Volstead Act. Concerns about privacy violations also extended to other instances where criminal sanctions were permitted for "victimless" crime, such as illegal gambling or narcotics violations.
Wolf v. Colorado (1949) ruled that states were not required to adopt the exclusionary rule. Despite the ruling, some states adopted the exclusionary rule. The California Supreme Court ruled in People v. Cahan (1955) that the exclusionary rule applied for cases in the state of California. By 1960, 22 states had adopted the rule without substantial qualifications: California, Delaware, Florida, Idaho, Illinois, Indiana, Kentucky, Mississippi, Missouri, Montana, North Carolina, Oklahoma, Oregon, Rhode Island, Tennessee, Washington, Texas, West Virginia, Wisconsin, Wyoming. Michigan also had an exclusionary rule, but with limitations for some narcotics and firearms evidence. In Alabama, Maryland, and South Dakota, the exclusionary rule applied in some situations.
The rule was expanded in the 1960s to cover other aspects of law enforcement procedure, including "involuntary" confessions, suspect identification obtained in violation of the Fifth and Sixth Amendments, wiretapping evidence in violation of federal law, and other evidence obtained through very unreasonable or "shocking" means in violation of Constitutional rights. In Illinois, People v. Albea (1954) ruled that testimony from witnesses found in course of an unlawful search cannot be admitted into court.
Even in a criminal case, the exclusionary rule does not simply bar the introduction of all evidence obtained in violation of the Fourth, Fifth, or Sixth Amendment. In Hudson v. Michigan, 547 U.S. 586, 126 S.Ct. 2159 (June 15, 2006), Justice Scalia wrote for the U.S. Supreme Court:
Suppression of evidence, however, has always been our last resort, not our first impulse. The exclusionary rule generates "substantial social costs," United States v. Leon, 468 U.S. 897, 907 (1984), which sometimes include setting the guilty free and the dangerous at large. We have therefore been "cautious against expanding" it, Colorado v. Connelly, 479 U.S. 157, 166 (1986), and "have repeatedly emphasized that the rule's 'costly toll' upon truth-seeking and law enforcement objectives presents a high obstacle for those urging [its] application," Pennsylvania Bd. of Probation and Parole v. Scott, 524 U.S. 357, 364-365 (1998) (citation omitted). We have rejected "indiscriminate application" of the rule, Leon, supra, at 908, and have held it to be applicable only "where its remedial objectives are thought most efficaciously served," United States v. Calandra, 414 U.S. 338, 348 (1974)
Limitations on the exclusionary rule have included the following:
- Evidence unlawfully obtained from the defendant by a private person is admissible. The exclusionary rule is designed to protect privacy rights, with the Fourth Amendment applying specifically to government officials.
- Evidence can only be suppressed if the illegal search violated the person's own (the person making the court motion) constitutional rights. The exclusionary rule does not apply to privacy rights of a third party.
- The defendant cannot take advantage of the situation (police breaching rules) to turn the case to their advantage, in face of other evidence against them.
- The Silver Platter doctrine applied before the Elkins v. United States ruling in 1960. State officials that obtained evidence illegally were allowed to turn over evidence to federal officials, and have that evidence be admitted into trial.
- If the court determines that the evidence obtained in the unlawful search would have been found in a later, warranted search, the evidence may be brought forth in court.
The exclusionary rule is not applicable to aliens residing outside of U.S. borders. In United States v. Alvarez-Machain, 504 U.S. 655, the U.S. Supreme Court decided that property owned by aliens in a foreign country is admissible in court. Certain persons in the U.S. receive limited protections, such as prisoners, probationers, parolees, and persons crossing U.S. borders. Corporations, by virtue of being, also have limited rights under the Fourth Amendment (see corporate personhood).
Hudson v. MichiganThe court in Hudson v. Michigan further held that a search whose only illegality is the failure to announce cannot uncover any evidence that would not have been uncovered if the announcement had been properly made, and therefore the suppression of evidence is not an appropriate remedy. The Court followed the general judicial trend, which views the exclusionary rule as a judicial remedy rather than a requirement under the Fourth Amendment. The Court there found that the costs of applying the exclusionary rule to the necessarily gray area of the "knock and announce" requirement were outweighed by the deterrence benefit. Over vigorous dissent the Court wrote, "But ignoring knock-and-announce can realistically be expected to achieve absolutely nothing except the prevention of destruction of evidence and the avoidance of life-threatening resistance by occupants of the premises—dangers which, if there is even "reasonable suspicion" of their existence, suspend the knock-and-announce requirement anyway. Massive deterrence is hardly required."
Limitations of the exclusionary rule have been criticized for reducing the effectiveness of rule in deterring police misconduct.
Herring v. United StatesIn 2008, the exclusionary rule will be reviewed again, in Herring v. United States. This case involves an individual, Bennie Herring, who was arrested after a neighboring law enforcement department found what they thought to be a warrant for skipping a court date on which the second department processed an arrest. The warrant was found to have been canceled, but not before further detention was made by the second department for drugs and a firearm (Herring was already a convicted felon and not allowed to have a firearm) found in Herring's possession. The evidence found during this arrest led to a 27-month prison term for Herring.
The issue to be decided is whether the good-faith exception to the exclusionary rule applies when a police officer makes an arrest after receiving information from a different law enforcement agency about an outstanding warrant, and the information was incorrect because of a negligent error by that agency. Two justices, Antonin Scalia and John Roberts, have already indicated that they would vote to rein in the exclusionary rule. Two lower courts have already ruled in favor of the government.
Exceptions to the ruleEven when the exclusionary rule does apply, the rule excludes the illegally obtained evidence only on the issue of the defendant's guilt for the particular crime charged. The evidence can still be admitted to impeach the credibility of the defendant's trial testimony; however, this exception applies only if the defendant testifies, and the evidence is relevant to call into question the truthfulness of the defendant's testimony.
The inevitable discovery doctrine is a direct exception to the exclusionary rule, in that it allows the admission of evidence on the issue of the defendant's guilt where the evidence would otherwise have been excluded. This doctrine was adopted first by the United States Supreme Court in Nix v. Williams in 1984. It holds that evidence obtained through an unlawful search or seizure is admissible in court if it can be established, to a very high degree of probability, that normal police investigation would have inevitably led to the discovery of the evidence. This decision was upheld because given the fact that the exclusionary rule was created specifically to deter police and state misconduct, excluding evidence that would inevitably (hypothetically) have been discovered otherwise would not serve to deter police misconduct. In People v. Stith, the Court stated that this doctrine may not be used to admit primary evidence but only secondary evidence—i.e., evidence found as a result of the primary evidence.
The attenuation exception to the exclusionary rule is that evidence may be suppressed only if there is a clear causal connection between the illegal police action and the evidence. The evidence must result from the unlawful conduct. A three-pronged test was created in People v. Martinez to determine whether there was sufficient attenuation of this connection (i.e. the lack of connection between the disputed evidence and the unlawful conduct): (1) the time period between the illegal arrest and the ensuing confession or consensual search; (2) the presence of intervening factors or event; and (3) the purpose and flagrancy of the official misconduct.
The independent source exception allows evidence to be admitted in court if knowledge of the evidence is gained from a separate, or independent, source that is completely unrelated to the illegality at hand. This rule was formally accepted in People v. Arnau.
The good-faith exception may allow some evidence gathered in violation of the Constitution if the violation results in only a minor or technical error. If a magistrate is erroneous in granting a police officer a warrant, and the officer acts on the warrant in good faith, then the evidence resulting in the execution of the warrant is not suppressible. However, there are a number of situations in which the good faith exception will not apply:
- No reasonable judicial officer would have relied on the affidavit underlying the warrant.
- The warrant is defective on its face for failing to state the place to be searched or things to be seized.
- The warrant was obtained based on an affidavit which, intentionally or recklessly, includes material falsehoods.
- The magistrate has "wholly abandoned his judicial role."
CriticismIn the 1970s, Dallin H. Oaks, Malcolm Wilkey, and others called for the exclusionary rule to be abolished. By the 1980s, the exclusionary rule remained controversial and was strongly opposed by President Ronald Reagan. But, some opponents began seeking to have the rule modified, rather than abolished altogether. The case, Illinois v. Gates, before the Supreme Court brought the exclusionary rule for reconsideration. The Supreme Court also considered allowing exceptions for errors made by police in good faith. The Reagan administration also asked Congress to ease the rule.