The exclusionary rule applies when evidence has been obtained illegally. That is, if the evidence is illegally obtained, then the evidence may not be considered at trial. This is one of the few remedies available to defendants who are subject criminal liability due to officer error.

Weeks v. United States

232 U.S. 383 (1914).


Whether the evidence should be returned to the defendant.


The evidence was improperly obtained, the conviction should not stand.


The defendant had been sending lottery tickets through the mail in violation of a federal criminal statute. Unknown to the defendant, the officers and marshal searched the defendant’s home without a warrant. From there, they took several papers proving the defendant had engaged in the activity (clearly an illegal search).


At the time of founding, the remedy for the error was a tort claim against the officer who engaged in the improper search. The natural result of this rule was that the evidence would be admitted. Here, however, the court says the failure to return the papers was in error so the evidence should be excluded. Why?

The Fourth Amendment is meaningless without a remedy. In other words, the Court was focused on judicial integrity.

Additional Notes

This rule was extended in Silverthorne Lumber Co. v. United States. There, the evidence was illegally obtained, returned, then legally obtained through a subpoena duces tecum. The Court determined the evidence was still excluded. This doctrine is called the “fruit of the poisonous tree.”

Even after the Fourth Amendment was incorporated and applied to states, they were still left to decide for themselves whether they would adopt the exclusionary rule (Wolf v. Colorado, 338 U.S. 25 (1949). Early after Weeks was passed, many of the states decided not to adopt the rule. The next case is an example of California changing their position.

People v. Cahan

282 P.2d 905 (Cal. 1955).


Whether the court should adopt the exclusionary rule.


The exclusionary rule is adopted.


Cahan and others were suspected of conspiracy to create books for horse-races against the state law. To gather evidence, officer’s snuck into Cahan’s house and set a recording wire under a nightstand. The recorded conversations led to the evidence that convinced the defendants (clearly an illegal search).


There are several benefits to having the non exclusionary rule: (1) Catch the bad guys, regardless of how the evidence was obtained, (2) there are other means of punishing officer’s for devastating investigative techniques, and (3) the non exclusionary rule does not punish the bad guy or the officer (both get off free).

However, there is one main issue with the non exclusionary rule, it is allowing officers to engage in improper investigative techniques in violation of the Constitution without any ramifications. Any attempts to discourage illegal searches have thus far proved ineffective. So, the Constitution is being violated, it’s hypocritical to be putting away bad guys while the officers are breaking the law, and no other means are working to resolve the issues. Thus, the court decides it is better to keep the sanctity of the Constitution, even if it means a few bad guys escape.

Additional Notes

In summary:

Those who want the exclusionary rule argue the rule is necessary because:

  • Judicial integrity – the court should not be involved in encouraging illegal searches.
  • Deterrence – Officers should be afraid of losing the evidence due to illegal searches.
  • Other remedies have not proved successful.

Those who want non exclusionary argue:

  • The evidence still has the same value of proving the crime regardless of how it is obtained.
  • It is costly to let law breakers go free because the evidence is excluded.
  • There is no evidence showing that deterrence has any effect.
  • There are other available remedies.

Mapp v. Ohio

367 U.S. 643 (1961).


Whether the exclusionary rule should apply to all states.


The exclusionary rule applies to all states.


Officers were informed that the defendant had material related to a recent bombing. When the officers came to her home, she demanded a warrant. They came back a few hours latter, broke into the home, and showed her a piece of paper they claimed was a warrant. When she snatched the paper, they arrested her and searched her home. Once again, clearly an illegal search.

The search produced illegal obscene material which was used to convict her of that crime (not the bombing). At trial and on state appeal, the evidence was not excluded because the state had not adopted the exclusionary rule unless there is a showing of brutal or excessive force.


In addition to the summary above, the Court shares additional insights about why they say the exclusionary rule should apply for all states.

First, the Court wants federal oversight to exist over the rule (just like in free speech or free press cases). Second, the Court wants uniformity between the states.

However, the dissent argues that the rule is not uniform because each state still has the freedom to apply the rule in different ways. Additionally, the textual intent of the Constitution provided tort claims as the remedy.

Additional Notes

  1. Judicial integrity is no longer a consideration justifying the rule. See U.S. v. Janis
  2. The exclusionary rule is not essential but is prudential to the Constitution. Therefore, the rule could be overturned with no concern and can be altered by Congress.

The content contained in this article may contain inaccuracies and is not intended to reflect the opinions, views, beliefs, or practices of any academic professor or publication. Instead, this content is a reflection on the author’s understanding of the law and legal practices.

Will Laursen

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