Illinois v. Gates

Following is the case brief for Illinois v. Gates, United States Supreme Court, (1983)

Case summary for Illinois v. Gates:

  • The police received an anonymous letter claiming that Mr. and Mrs. Gates were running an illegal drug business and outlining future action.
  • Upon receiving the letter, police further investigated and it was determined that most of the informants tips were correct with the exception of one fact. The police obtained a judge issued warrant.
  • The defendants challenged their charges claiming the search was based on an unlawful search warrant.
  • The Court held that because the informant letter was accurate regarding the defendants’ future plans, the magistrate’s warrant reasonably took into consideration the totality of the circumstances and assumed the veracity of the informant in regards to the allegations.

Illinois v. Gates Case Brief

Statement of the facts:

In response to an anonymous letter detailing the Gates’ illegal drug business, police conducted their own investigation. The investigation, which included surveillance, confirmed most of the informant’s tips as true with the exception of one fact. After securing a search warrant, the police searched the defendants house and car, where weapons, drugs and other contraband were found. The defendants challenged the search, claiming it was unlawful and the trial court judge ordered suppression of all the evidence.

Procedural History:

The trial court found for the defendants and the state appealed. Both the state appellate and the state supreme court affirmed the lower court’s decision. The state then appealed to the Supreme Court of the United States, who granted certiorari.

Rule of Law or Legal Principle Applied:

A warrant is Constitutional under the Fourth Amendment’s probable cause requirement when is establishes a substantial basis that the search will uncover evidence of the wrongdoing.

Issue and Holding:

Whether a warrant based on partially corroborated evidence divulged from an unknown informant can satisfy the Fourth Amendment’s probable cause requirement? Yes.


The Court reversed the state supreme court’s judgment.


  • The Court held that statements corroborated by an unknown informant can provide sufficient probable cause, satisfying the Fourth Amendment.

The Court referred to a “rigid” two part test set out in Aguilar v. Texas, 378 U.S. 108 (1964), and Spinelli v. United States, 393 U.S. 410 (1969) which determines whether or not probable cause exists. First, the judge must consider the veracity or reliability of the informant. The next step is to consider how the informant learned of the information.

The Court held this approach is too technical because it forces judges to look at issues separately when it is more reasonable to consider them together. This should be accomplished through applying a totality of the circumstances test. The Court decided a totality of the circumstances test is preferable since a court decision should be regarded with great deference when reviewed by other courts. The Court pointed out how affidavits are drafted by non-lawyers and that the requirements outlined in the two step approach does not assist a judge or magistrate in establishing probable cause.

In addition, police officers may be deterred from seeking warrants in the first place due to the strict standard of scrutiny of the two prong test. As a result, such apprehension could interfere with the police ability to protect and serve.

In this case, applying the totality of the circumstances equates to probable cause.  The warrant was issued properly and although the anonymous letter alone is not sufficient to establish probable cause, it is when coupled with the detective’s affidavit corroborating parts of the letter predicting the defendants future steps.

Concurring or Dissenting opinions:

Concurring (White):

The Court wrongfully overturned precedent. The warrant was properly issued under the initial two part test.

Dissenting (Stevens):

Since the issuing magistrate knew the informant was wrong about a material detail when the warrant was issued, the warrant was improper.

Dissenting (Brennan):

The Court was wrong to overturn existing precedent and the decision prioritizes efficiency over individual constitutional rights. The totality of the circumstances test risks limiting the magistrates role as an independent arbiter and takes away the relied upon existing structure of issuing warrant. Jeopardizing the accuracy of probable cause determinations result.


Illinois v. Gates set the current precedent for search warrant requirements that are based on an anonymous informant. The judicial officer must consider the totality of the circumstances and is no longer limited to the two pronged test.

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