The Illinois v. Gates decision in 1983 overturned the Aguilar-Spinelli test in favor of a totality of the circumstances approach for determining whether or not probable cause exists. The Aguilar-Spinelli test was established by Aguilar v. Texas (1964) and Spinelli v. United States (1969) and held that in order for an informant’s tip or letter to be used as probable cause for obtaining a search warrant, two prongs must be met. Primarily, the tip had to “reveal adequately the informant’s basis of knowledge.” In other words, the tip had to identify how the individual came to possess the knowledge. Secondly, the tip had to provide facts that would determine the veracity and the reliability of the informant’s information.
In the Illinois v. Gates case, the police received an anonymous letter on May 3, 1978 that claimed Sue and Lance Gates were transporting drugs from Florida and then selling them in Illinois. Specifically, the tip stated that Sue would drive their car to Florida where she would obtain the drugs, then Lance would fly down to drive the car back. The letter also claimed that the couple was about to embark on another drug trafficking excursion. When police received this information, they verified that Lance Gates had a flight reservation to West Palm Beach and proceeded to survey him in Florida. After discovering that Lance met his wife and immediately drove back with her to Illinois, the police obtained a warrant to search the couples’ car and home. During the search they found evidence of drug trafficking. However, at pretrial, the defense argued that the Aguilar-Spinelli bar had not been met because the tip did not explain how the informant became aware of the information he provided to police and therefore there was not sufficient probable cause. The Illinois Supreme Court affirmed the decision. Once the case made it to the Supreme Court, the legal question was whether or not a partially verified anonymous informant’s tip could establish the probable cause to obtain a warrant pursuant to the unreasonable search and seizure clause of the 4th Amendment. With a vote of 6 to 3, the Supreme Court reversed the ruling of the Illinois Supreme Court and determined that a partially corroborated tip could be the basis of probable cause.
Overall, I agree with the court’s decision. As Justice Rehnquist articulates in the majority opinion, the veracity, reliability and basis of knowledge components of an informant’s tip should not be treated as distinct standards that must be met before probable cause is established. Instead, looking at these three elements concurrently is sufficient for a judge to determine whether or not there are enough facts for a reasonable person to conclude that someone may have committed a crime, thereby establishing probable cause. While Justice Brennan’s dissenting opinion is well-taken, I do not believe that revoking the Aguilar-Spinelli test would diminish the intended purpose of probable cause. Justice Brennan contends that without a structure to determine probable cause, there is a risk of judges issuing warrants based on insufficient, unreliable information from dishonest sources, which would therefore be tantamount to police and informants, as opposed to magistrates, determining probable cause. However, simply because an anonymous informant’s tip can be used to establish probable cause does not mean that these tips will provide probable cause in every circumstance. A judge must still make the determination as to whether or not there is probable cause, and therefore, even if this decision makes probable cause from informants easier to be obtained, a judge still acts as a check against unreasonable search and seizures. While it is true that this decision would make it easier for law enforcement to obtain warrants in certain situations, I do not agree with the court’s opinion simply because the Aguilar-Spinelli test had impeded law enforcement before Illinois v. Gates. Instead of focusing on the difficulty for law enforcement to obtain a warrant, I believe the more important question is how to conceptualize probable cause and whether or not that conceptualization will detract from the rights of the criminally accused. In answering the first part of this question, I agree with the majority opinion that probable cause should be considered a fluid concept, in which a judge can weigh the veracity and reliability in relation to the informant’s basis of knowledge. Therefore, in establishing probable cause, I do not believe that it is necessary to determine the source of every underlying fact within the informant’s tip. If a judge believes that a partially verified tip can lead a reasonable person to believe a crime may have been committed, then the bar for probable cause is met. Furthermore, both because the bar for determining probable cause is far lower than the bar needed to prove the burden in a criminal, or even civil, procedure and because a judge and not law enforcement must make the ultimate determination of probable cause, I do not believe that an individual’s rights would be violated by a search in which the warrant used to conduct that search used the totality of the circumstances approach as opposed to the Aguilar-Spinelli standard to establish probable cause.