Exclusionary Rule

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One of the cornerstones of US constitutional protections is the exclusionary rule. The exclusionary rule states that evidence obtained as a result of an illegal search or seizure or illegal interrogation is not admissible against the victim in a criminal proceeding. There are several rationales behind the rule, including: 1) deterrence of law enforcement officials from engaging in prohibited conduct given that valuable evidence will be lost if such conduct ensues; and 2) preservation of judicial integrity through preventing taint of the court by unlawful police conduct.

The exclusionary rule was applied to United States federal courts in Weeks. v. United States, 232 U.S. 383 (1914). The principal was later incorporated against the states in Mapp v. Ohio, 367 U.S. 643 (1961). The rule excludes evidence regardless of whether the violation is conducted by a state or federal official, and regardless of whether the criminal prosecution is brought in a state or federal court. On the other hand, the exclusionary rule generally does not apply beyond the criminal trial itself. The court will weigh the cost of excluding the illegally obtained evidence against the deterrent benefit of extending the rule to the new situation.[1] For example, evidence seized unconstitutionally may be admissible in proceedings both before and after trial. Such proceedings include grand jury proceedings, preliminary hearings, bail hearings, sentencing hearings and parole hearings.

Example: Baltimore Police break into defendant’s home without a warrant or applicable exception to the warrant requirement, finding a small amount of marijuana in the defendant's sock drawer. The evidence will be inadmissible because the evidence was found pursuant to an illegal search in violation of the defendant's Fourth Amendment Rights.

Fruit of the Poisonous Tree

Under the fruit of the poisonous tree doctrine, any additional evidence obtained as a result of illegally obtained evidence must also be excluded from trial.

In Wong Sun v. United States, 371 U.S. 471 (1963) the U.S. Supreme Court refused to hold that “all evidence is 'fruit of the poisonous tree' simply because it would not have come to light but for the illegal actions of the police." The question, said the Court, is "whether, granting establishment of the primary illegality, the evidence to which the instant objection is made has been come at by exploitation of that illegality or instead by means sufficiently distinguishable to be purged of the primary taint." In other words, courts must determine whether the evidence in question was obtained through exploitation of the illegally obtained evidence or through means sufficiently separate from the tainted evidence. Later, courts recharacterized the test as "attenuation" rather than "taint".

Example: The defendant was suspected of murdering a child. The defendant’s attorney advised the defendant to turn himself in, but to speak with police only when the attorney was present. The attorney also conveyed to the police that the defendant was not to speak with the police outside of his presence. While being transported by police officers, and without his attorney, the officers appealed to the defendant’s deep religious convictions. Thus, the defendant confessed and led the officers to the victim’s body. The confession was held inadmissible because the defendant’s rights were violated when the police persuaded him to lead them to the body. Evidence of the body was held admissible because its discovery was inevitable due to close proximity of search parties to the body. [2]

Illegal Interrogations and Illegal Searches and Seizures

Generally, the exclusionary rule applies in two different circumstances:

First, the exclusionary rule may apply to confessions when counsel proves the circumstances surrounding the interrogation were such that either the defendant's rights were violated or the interrogation was so coercive that the evidence is no longer reliable.

Second, the exclusionary rule may apply to evidence obtained by an illegal search or stop even though the evidence would otherwise be completely reliable. The rationale behind this second rule is twofold: 1) the government should not benefit from violating a country's laws, and 2) the hope that the exclusionary rule will deter future rights violations.

While many countries have some version of the exclusionary rule, the United States is unique because it is the only country in which the rule is mandatory for both illegal interrogations and illegal searches and seizures.

International Standards Governing Exclusion of Illegal Evidence


Prior to 2010 Chinese criminal procedure was silent on the issue of whether illegally obtained evidence was admissible against the defendant. However in June of 2010 the Supreme Court of China issued Rules Concerning Questions About Exclusion of Illegal Evidence in Handling Criminal Cases, a set of comprehensive rules governing the use of illegal evidence in criminal cases.

Rules for Illegal Interrogations

On June 25, 2010, China's Supreme People's Court, Supreme People's Procuratorate, Ministry of Public Security, Ministry of State Security, and Ministry of Justice formally published Rules Concerning Questions About Exclusion of Illegal Evidence in Handling Criminal Cases.

Under these rules, oral evidence obtained through illegal means such as coerced confessions and witness or victim testimony obtained through the use of violence or threats must be excluded.[3]Furthermore, the people's procurator may not use the evidence as the basis for approving arrest or initiating prosecution.[4] The rule is silent as to whether the fruits of an illegal confession can be used against the defendant if the oral evidence is excluded from trial. Nor do the rules indicate whether the evidence can be used to impeach the defendant.

Rules for Illegal Searches and Seizures

The rules do not indicate that evidence procured from an illegal search or seizure would be deemed inadmissible.


The closest concept to the exclusionary rule in French criminal procedure is the concept of nullities.

Nullity of Procedures

Textual Nullity - Textual nullity applies when a rule explicitly provides for the exclusion of evidence if the procedure is violated. Because textual nullity rules are mandatory, the court must also prohibit the use of all fruits of the illegal procedure.

Substantial Nullity - In all other cases, a nullity procedure may be used if the government violates a "substantial" provision of the code. A defendant generally must show actual harm or standing, however, this need not be proven if the procedural error harmed public order.

Involuntary Confessions

Even if all formal criminal procedures are done correctly, a confession may still be inadmissible if it is extracted using torture or deceptive investigatory techniques.

South Africa

In 1994, the enactment of South Africa’s Interim Constitution created an equivalent to the U.S. Bill of Rights. The 1996 constitution was very progressive and borrowed heavily from international instruments and U.S. legal constructs such as Miranda warnings. Prior to the Interim Constitution, the general rule was that all relevant evidence was admissible. Evidence was only excluded if the defendant proved a deliberate violation of his or her rights.

Section 35(5) of the Constitution forms the basis for the exclusionary rule in South Africa:

Evidence obtained in a manner that violates any right in the Bill of Rights must be excluded if the admission of that evidence would render the trial unfair or otherwise be detrimental to the administration of justice.

Rules for Illegal Interrogations

As in most jurisdictions, involuntary statements are inadmissible in South African courts. In addition, South Africa has adopted progressive Miranda-style warnings that are required prior to the interrogation of individuals. Thus, failure to deliver the warnings may also result in the inadmissibility of evidence.

Rules for Illegal Searches and Seizures

Searches and seizures of evidence are covered under Section 35(5) of the Constitution of South Africa. Under this rule exclusion is mandatory if the court finds that one of two conditions is met:

  1. The evidence would render the trial unfair
  2. Admitting the evidence would prove detrimental to the administration of justice

In certain respects, this provision is broader than the U.S. equivalent. For one, the standing requirement that limits the exclusionary rule in the United States does not apply in South Africa.

United States

Exceptions to the Exclusionary Rule

The United States Supreme Court has slowly eroded several cornerstones of the exclusionary rule. Many academics now consider the rule to be in danger. The following exceptions to the rule generally apply:

  • Independent Source Doctrine: Evidence is admissible if the government obtains evidence from a source independent of the illegal search or seizure.[5]
  • Inevitable Discovery Doctrine: A variant of the "independent source" exception, stating a court may hold that the exclusionary rule does not apply if discovery of the evidence was certain regardless of the error. Generally, the mere notion that the evidence may have been discovered is not sufficient to trigger the exception. Thus, if the government can prove that discovery was inevitable, regardless of the illegal conduct, it may be admitted under the inevitable discovery doctrine.[6]
  • Confessions: Confessions resulting from an illegal seizure (defendant compelled to confess outside the presence of an attorney, after requesting an attorney) will be excluded from evidence. Nonetheless, confessions resulting from an illegal search or seizure are admissible if the link between the illegal conduct by the police and the challenged evidence is weak. For example, the police have probable cause to arrest an individual; they arrest the individual at home, without a warrant, and he thus confesses to the crime. This evidence would likely not be suppressed, particularly if the defendant were told of his right to remain silent and his right to counsel. The rationale behind this rule is that the exclusionary rule is meant to deter police misconduct. If the link between the misconduct and the evidence is weak, then there is little use of applying the exclusionary rule.
  • Good Faith: In United States v. Leon the U.S. Supreme Court concluded that the exclusionary rule does not apply to officers acting with an objectively reasonable belief that their conduct was not violating the defendant’s rights. For the exception to apply, good faith generally requires the existence of a search warrant issued by a neutral magistrate based on probable cause. The exception applies even if the appeals court determines sufficient probable cause did not exist to issue a warrant. There are four exceptions to this rule:
  1. Affidavit is so lacking in probable cause that no reasonable police officer would have relied on it.
  2. Warrant is defective on its face (fails to state with particularity the place to be searched or the things to be seized).
  3. Police officer or government official obtaining the warrant lied to or misled the magistrate.
  4. Magistrate has wholly abandoned his role.
  • Standing: In Rakas v. Illinois the U.S. Supreme Court held that a person who is aggrieved by an illegal search or seizure, which occurred only through evidence secured by a search of a third person's premises or property has not had any of his fourth amendment rights infringed. Therefore, the defendant cannot use the exclusionary rule to prevent the evidence from being admitted at trial.
  • Civil Suits: Generally, the exclusionary rule only applies in criminal proceedings. Thus, the evidence may be admissible in a civil suit against the defendant for damages.
  • Knock and Announce: In Hudson v. Michigan (2006), the U.S. Supreme Court concluded that a violation of the knock and announce rule does not require the exclusion of any evidence obtained pursuant to the search. The court concluded that the causal connection was remote and suppression would not serve the interest protected by the constitutional guarantee. After this case was decided, many academics warned that the Supreme Court would soon overrule the exclusionary rule, or replace it with a social costs balancing test.
  • Evidence from Outside the Country: In United States v. Alvarez-Machain, the U.S. Supreme Court held that an extradition treaty with Mexico does not bar jurisdiction of US court where defendant was forcibly extracted from Mexico. Treaty has no explicit prohibition and does not state that extradition is exclusive method of extraction.


Section 244 of the German Code of Criminal Procedure vests authority in the court to limit the admissibility of evidence. Section 244(3) states “[a]n application to take evidence shall be rejected if the taking of evidence is inadmissible.” Thus, the criminal court is required to reject an application if the evidence was illegally obtained. Section 136a of the Code of Criminal Procedure stipulates that in the preliminary inquiry the accused’s freedom to make up his or her mind and to manifest his will shall not be impaired by ill-treatment, induced fatigue, etc… Statements obtained in breach of this prohibition shall not be admitted into evidence, even if the accused agrees to their use. Evidence collected by creating an interference with fundamental rights will be admissible depending on whether the interference has some base in a special law rescuing it from inadmissibility.[7]

The Federal Constitutional Court of Germany requires determination of evidence admissibility through a balancing test that considers respect for human dignity in light of the severity of the crime being investigated. In particular, the Court ruled that there is a presumption in favor of the accused in certain circumstances that require a strict evaluation in favor of the accused. Such circumstances include searches and seizures within the accused’s home or conversations between the accused and a person “within his or her inner private sphere.” Nonetheless, the Court elaborates, “where no connection between a specific conversation and an individual’s inner private sphere exists, such conversations will not affect the human dignity aspect of the fundamental right.”[8]


Similar to Germany, Spain incorporates the exclusionary rule into criminal justice procedure through weighing the importance of preserving a fundamental right, such as right to privacy or right to a fair trial, and the reason for sacrificing such right.[9]

Further, Spain protects fundamental rights by evaluating the admissibility of evidence in a criminal trial through the prism of the “principle of proportionality.” Thus law enforcement agencies prior to collecting the evidence in question must prove 1) they are capable of producing the desired outcome; 2) the least intrusive alternative capable of delivering that outcome is being utilized; and 3) the intrusion must be proportionate to the benefit derived from the measure. Therefore, the principle requires a judge to consider not only the seriousness of the offense, but to also strictly adhere to the guarantees provide by a specific and reasoned judicial authorization.[10]

European Court of Human Rights

The European Court of Human Rights adopted the position that the use of illegally obtained evidence does not necessarily lead to unfair proceedings.[11] The position of the Court is that it should generally be left to national courts to decide on the admissibility of evidence. Nonetheless, the Court ruled, “The question which must be answered is whether the proceedings as a whole, including the way in which the evidence was obtained, were fair.”[12] The court went on to explain that determining admissibility involves an examination of the alleged unlawfulness in question and the nature of the violation. Thus the fairness of a trial is not necessarily corroded by the use of illegally obtained evidence.

In general, national rules of criminal procedure are more protective of the accused than the European Convention on Human Rights. Only seven States (Austria, Denmark, Finland, France, Germany, Sweden and the United Kingdom) admit evidence obtained in violation of the right to respect for private life. In most other member States, such evidence would not normally be admissible.

See Rights of the Accused, Evidence, Defenses


  1. United States v. Calandra, 414 U.S. 338 (1974).
  2. Nix v. Williams, 467 U.S. 431 (1984).
  3. Rule 1, Rules Concerning Questions About Exclusion of Illegal Evidence in Handling Criminal Cases, China's Supreme People's Court, Supreme People's Procuratorate, Ministry of Public Security, Ministry of State Security, and Ministry of Justice, June 25, 2010.
  4. Rule 2, Rules Concerning Questions About Exclusion of Illegal Evidence in Handling Criminal Cases, China's Supreme People's Court, Supreme People's Procuratorate, Ministry of Public Security, Ministry of State Security, and Ministry of Justice, June 25, 2010.
  5. United States v. Crews, 445 U.S. 463 (1980)
  6. Nix v. Williams, 467 U.S. 431 (1984).
  7. Raneta Lawsom Mack, Comparative Criminal Procedure: History, Processes and Case Studies.
  8. Federal Constitutional Court, Germany, 1 BvR 2378/98 (2004).
  9. Spain Constitutional Court, First Chamber 26-03-1996 54/1996.
  10. Raneta Lawsom Mack, Comparative Criminal Procedure: History, Processes and Case Studies.
  11. Eur. Ct. HR, Schenk v. Switzerland Judgement of 12 July 1988, Series A no. 140, and Eur. Ct. HR (3d sect.), Khan v. the United Kingdom (Appl. No 35394/97), ECHR 2000-V, judgement of 12 May 2000.
  12. P.G. and J.H. v. the United Kingdom, judgment of 25 September 2001.