The Aguilar-Spinelli test-Background

According to the Fourth Amendment to the U.S. Constitution:

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

Historically in the United States, if the police made an illegal search and seizure of evidence, the evidence, once obtained, could often be used against a defendant in a criminal trial regardless of its illegality.

By a unanimous decision in the case of Weeks v. United States (232 U.S. 383) (1914),^[2] the Supreme Court created the “exclusionary rule.” This rule declared that, in most circumstances, evidence obtained through an illegal search and seizure could not be used as admissible evidence in a criminal trial. (This decision created the rule only on the federal level. It was not until Mapp v. Ohio (367 U.S. 643) (1961)^[3] that the exclusionary rule was held to be binding on the states.)

Subsequently, the defense in many criminal trials attempted to prove that a search warrant was invalid, thus making the search illegal and hence the evidence obtained through the search inadmissible in the trial. However, there were no hard guidelines defining the legality of a search warrant and it could be difficult for a judge to decide upon a warrant’s validity.

In order to obtain a search warrant in the United States, a law officer must appear before a judge or magistrate and swear or affirm that he has probable cause to believe that a crime has been committed. The officer is required to present his evidence to the magistrate and present an affidavit to the magistrate, setting forth his evidence. “An affidavit must provide the magistrate with a substantial basis for determining the existence of probable cause.” In other words, the law officer must present his evidence, not merely his conclusions. “Sufficient information must be presented to the magistrate to allow that official to determine probable cause; his action cannot be a mere ratification of the bare conclusions of others.”^[4]

In Johnson v. United States (333 U.S. 10) (1948), the Court said:

In The point of the Fourth Amendment, which often is not grasped by zealous officers, is not that it denies law enforcement the support of the usual inferences which reasonable men draw from evidence. Its protection consists in requiring that those inferences be drawn by a neutral and detached magistrate instead of being judged by the officer engaged in the often competitive enterprise of ferreting out crime.^[5]

Development of the two-pronged test

In Aguilar v. Texas (378 U.S. 108) (1964), the Court said:

[T]he magistrate must be informed of some of the underlying circumstances relied on by the person providing the information and some of the underlying circumstances from which the affiant concluded that the informant, whose identity was not disclosed, was creditable or his information reliable.^[6]

In Spinelli v. United States (393 U.S. 410) (1969), the Court went further and stated that the magistrate must be informed of the “underlying circumstances from which the informant had concluded” that a crime had been committed.^[7]

Footnotes

1. ↑ Spinelli v. United States (393 U.S. 410)
2. ↑ Weeks v. United States (232 U.S. 383)
3. ↑ Mapp v. Ohio (367 U.S. 643)
4. ↑ Illinois v. Gates (462 U.S. 213, 238)
5. ↑ Johnson v. United States (333 U.S. 10)
6. ↑ Aguilar v. Texas (378 U.S. 108)
7. ↑ Spinelli v. United States (393 U.S. 410)
8. ↑ Illinois v. Gates (462 U.S. 213, 214)

http://en.wikipedia.org/wiki/Aguilar-Spinelli_test#Background