Legal Definitions - Aguilar–Spinelli test

The Aguilar–Spinelli test was a legal standard formerly used by courts to determine if information provided by an informant, often hearsay (second-hand information), was reliable enough to establish "probable cause" for police to obtain an arrest warrant or a search warrant. Probable cause means there's a reasonable basis to believe a crime has been committed or that evidence of a crime exists in a particular location.

This test required a judge to evaluate the informant's tip using two independent criteria, often called "prongs":

• The "basis of knowledge" prong: This assessed how the informant came to know the information. Did they personally witness the events, or were they merely repeating a rumor? The information needed to show a clear, non-speculative origin.
• The "veracity" or "reliability" prong: This assessed the credibility of the informant themselves. Was the informant known to be trustworthy? Had they provided accurate information in the past? Were there any reasons to believe they were telling the truth (e.g., providing information against their own interest)?

For probable cause to be established, both prongs had to be satisfied independently. If either the source of the information or the informant's credibility was found lacking, the tip alone could not justify a warrant. It's important to note that while historically significant, the Aguilar–Spinelli test has largely been replaced by a more flexible "totality-of-the-circumstances" approach, which allows judges to consider all available facts together rather than strictly separating these two prongs.

Examples:

1. Evaluating a Drug Trafficking Tip for a Search Warrant (Historical Context)

Imagine in the 1970s, a police detective received an anonymous phone call claiming that "John Doe is selling large quantities of illegal substances from his apartment at 123 Main Street." The caller stated they had personally seen bags of white powder and scales inside the apartment during a recent visit. To obtain a search warrant under the Aguilar–Spinelli test, a judge would have to assess this tip:

• Basis of Knowledge: The caller claimed to have personally seen the drugs and scales, suggesting direct observation rather than mere speculation. This would likely satisfy the "basis of knowledge" prong.
• Veracity/Reliability: However, the caller was anonymous. There was no way for the police or the judge to assess their past reliability, credibility, or motives. Without any corroborating information about the caller's trustworthiness, the "veracity" prong would likely fail.

Because the veracity prong failed due to the anonymous nature of the tip, a judge applying the Aguilar–Spinelli test would likely have denied the search warrant, as the tip alone would not establish probable cause.

2. Informant's Tip for an Arrest Warrant

Consider a scenario from the late 1960s where a known police informant, who had provided accurate tips in the past leading to several successful arrests for property crimes, told officers that "Mark Johnson confessed to me that he was the one who broke into the electronics store last night and stole the televisions." The informant further explained that Mark had shown them one of the stolen televisions hidden in his garage.

• Basis of Knowledge: The informant stated that Mark confessed directly to them and showed them stolen goods. This indicates direct knowledge of the crime and the evidence, satisfying the "basis of knowledge" prong.
• Veracity/Reliability: The informant was known to the police and had a track record of providing reliable information in similar cases. This established their credibility, satisfying the "veracity" prong.

In this case, because both prongs of the Aguilar–Spinelli test were met, a judge would likely have found probable cause based on the informant's tip, allowing for the issuance of an arrest warrant for Mark Johnson.