Informants, Use of

An informant is any individual who provides police or government officials with information that will aid in the discovery of criminal activity, evidence, or perpetrators of a crime. Some informants witness criminal activity and step forward out of a sense of public duty. Others, who may themselves be involved in crime, provide information in hopes of financial reward or lenient treatment for crimes that they have committed. The reliability and even the use of informants, however, has been called into question, especially when informant-provided information is offered to establish probable cause for a search warrant.

Both federal and state courts have evaluated and answered judicial questions about information provided by informants and used by police in proving probable cause to search and seize evidence. Some courts distinguish between so-called citizen informants and those in the criminal milieu. Courts often assume that there is greater reliability for citizen informants. The two-pronged test, called the Aguilar-Spinelli test, for determining the admissibility of informant testimony in a search-and-seizure case was prescribed in two separate cases: Aguilar v. Texas (1964) and Spinelli v. United States (1969).

The first prong involves the basis of the informant's knowledge of the crime as well as of the accused. Under this prong, a judge determines whether the police's assertion of probable cause, necessary to issue a warrant—the explicit Fourth Amendment criterion for such an action—is valid. That is, the police must verify to the judge that the specific details provided by the informant are consistent with the crime being investigated and that the informant is credible.

The second prong of the test is based on weighing the veracity of the information provided against the likelihood that the informant is lying or giving false information. The courts have often held information provided by anonymous informants to stricter standards under this prong. This standard is often not applied when the informant is the witness to a crime or a victim of criminal activity.

The requirements spelled out in Aguilar and Spinelli were tested in McCray v. Illinois (1967). In this case, the Supreme Court's application of the Aguilar-Spinelli test resulted in the Court's decision that a warrant issued to an officer, who said he knew the informant for almost one year and had received credible information fifteen or sixteen times that resulted in arrests and convictions, was valid.

The courts have continually demonstrated their interest in protecting informant identity and security and in preserving their function in crime solving. The role of law enforcement and the value of informants were supported by the Supreme Court in Illinois v. Gates (1983) when the justices determined that the two-pronged Aguilar-Spinelli test put too heavy a burden on police by requiring an excessively technical dissection of informant's tips.

In light of the Gates decision, less restrictive standards than the two-pronged measure have been applied to determine whether the use of an informant's intelligence is substantial enough to prove probable cause prior to issuing a warrant. Describing the new standard, the Supreme Court found in Gates that judges should take into account the “totality of circumstances” when determining the reliability of information provided by an informant. Determining the totality of the circumstances allows warrant-issuing judges or magistrates to weigh factors such as the informant's knowledge of the crime, of the criminal or criminals associated with the crime, and of the crime and crime scene as well as the informant's veracity. Under these standards, in making a decision with regard to probable cause to issue a warrant, judges and magistrates may evaluate the information from an informant regardless of whether the police demonstrate specific knowledge of or personal history with the informant.

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