Use Of Informants And Confidential Sources
Informants and confidential sources are individuals who provide law-enforcement agencies with information about crimes or criminal suspects. Courts closely regulate the use of informants because they operate in legally sensitive areas, including:
Entrapment
Fourth Amendment search and seizure
Reliability of tips
Privilege of informant identity
Due process and fair trial rights
Below are major doctrines governing the use of informants, explained alongside leading case laws.
1. McCray v. Illinois (1967) — Informant Identity & Probable Cause
Key Issue:
Whether police must reveal an informant’s identity during a suppression hearing challenging probable cause.
Facts:
Police arrested McCray based on information provided by a confidential informant who claimed McCray possessed narcotics. McCray argued that probable cause could not be established unless the informant testified.
Holding:
The Supreme Court held that police are not required to disclose an informant’s identity during probable-cause hearings, as long as the judge is satisfied that the officers acted in good faith.
Importance:
Established that the informant’s privilege protects anonymity in certain proceedings.
Allowed police to rely on credible informants without exposing them.
Differentiated between trials (where due process concerns may require disclosure) and preliminary issues like probable cause.
2. Aguilar v. Texas (1964) — Reliability of Informant Tips (Two-Prong Test)
Key Issue:
When is an informant’s tip sufficient to establish probable cause for a warrant?
Facts:
Police obtained a search warrant based solely on officers’ assertions that they received information from an informant. The warrant lacked any description of how the informant knew the information or why the police considered them reliable.
Holding:
The Court struck down the warrant and created the Aguilar Two-Prong Test:
Basis of Knowledge: How did the informant obtain the information?
Veracity or Reliability: Why should the informant be trusted?
Importance:
Required courts to independently evaluate the foundation of informant tips.
Prevented officers from relying on uncorroborated, vague informant claims.
Formed the basis for later cases refining informant reliability standards.
3. Spinelli v. United States (1969) — Reinforcing Aguilar, Need for Corroboration
Key Issue:
The level of corroboration required when an informant’s tip is weak or lacking.
Facts:
FBI sought a warrant to search Spinelli for gambling evidence. The affidavit relied on an informant’s statement but offered very little detail. Police attempted to use minimal surveillance to “fill in the gaps.”
Holding:
The Supreme Court held the warrant invalid. The Court emphasized:
General or innocent conduct does not corroborate an informant’s claims.
Vague, unsupported assertions do not meet the Aguilar standard.
Importance:
Strengthened the Aguilar-Spinelli Test for validating informant-based warrants.
Required meaningful corroboration when informant information is weak.
Prevented superficial investigations used to rubber-stamp warrants.
4. Illinois v. Gates (1983) — The “Totality of the Circumstances” Test
Key Issue:
Should courts continue using the Aguilar-Spinelli rigid test?
Facts:
Police received an anonymous letter detailing a couple’s drug trafficking scheme. Much of the tip was verified by police surveillance before obtaining a search warrant. Lower courts invalidated the warrant under Aguilar-Spinelli.
Holding:
The Supreme Court abandoned the strict Aguilar-Spinelli test and adopted the Totality of the Circumstances test:
Judges must look at all factors together, including partial corroboration, informant detail, and officer experience.
Reliability and basis of knowledge still matter but are not rigid requirements.
Importance:
Made it easier for law enforcement to use informant tips.
Allowed deficiency in one area (e.g., reliability) to be offset by strength in another (e.g., detailed predictions corroborated by police).
Is now the leading standard for evaluating informant tips in the U.S.
5. Roviaro v. United States (1957) — Disclosure of Informant Identity at Trial
Key Issue:
When must the government reveal the identity of a confidential informant?
Facts:
Roviaro was charged with narcotics violations. The informant was present during the alleged transaction and directly participated. The government refused to disclose the person’s identity.
Holding:
The Court ruled that the government must disclose an informant’s identity when it is essential to ensuring fairness, especially when:
The informant is a participant,
A key witness, or
Critical to the defense’s ability to challenge the prosecution’s case.
Importance:
Established a balancing test: public interest in protecting informants vs. defendant’s right to a fair trial.
Limits the government’s privilege to withhold informants’ identities.
Critical in cases where entrapment or direct witness testimony is involved.
6. United States v. White (1971) — Informants and Electronic Monitoring
Key Issue:
Does a suspect have a Fourth Amendment expectation of privacy against conversations secretly recorded by an informant wearing a wire?
Facts:
An informant recorded conversations with White using a hidden transmitter. White argued this violated his Fourth Amendment rights.
Holding:
The Supreme Court ruled that a person takes the risk that whoever they are speaking to may be:
An informant,
Cooperating with police, or
Recording or transmitting the conversation.
Thus, no warrant is required for informants wearing recording devices.
Importance:
Legalized the widespread use of wired informants.
Affirmed that the Fourth Amendment does not protect misplaced trust.
Significant for undercover operations involving surveillance.
SUMMARY OF LEGAL PRINCIPLES
1. Informant Identity
Protected generally (McCray).
Must be disclosed if critical to defense (Roviaro).
2. Reliability & Probable Cause
Aguilar-Spinelli Test (Aguilar, Spinelli).
Evolved into Totality of Circumstances (Gates).
3. Surveillance and Electronic Monitoring
Informant recordings do not violate Fourth Amendment (White).
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