Illinois v. Gates
Supreme Court of the United States 1983

Facts

Defendants Lance and Susan Gates were indicted for violation of state drug laws after police, executing a Search Warrant, discovered marijuana and other contraband in their automobile and home.

Police received an anonymous tip which detailed how the Gates' made their drug deals. The letter claimed that Sue would drive the car to Florida where it is loaded up with drugs. Then Lance would fly to Florida and drive the car back, and Sue would fly home. It specified dates on which they would be making their next run.

Police followed up on the tip, and, with the assistance of the DEA, surveyed the Flight on which Lance was supposedly flying to Florida. Surveillance showed Lance Gates arriving in Florida, staying in a local motel, and heading out with a woman on a road that was frequently used by travelers to the Chicago area. Police applied for and obtained a search warrant fro the Gates' home and basement, on the basis that their modus operandi had been confirmed. When the Gates returned two days later, police searched their car and home and found 350 pounds of marijuana and other contraband. The Gates moved to suppress the evidence on the basis that the affidavit did not establish probable cause. The State Courts suppressed the evidence on the basis that the anonymous letter did not satisfy the two-pronged test derived from Spinelli, that; 1) the Tip had to reveal the "basis of knowledge" of the tipster, and 2) that the veracity (or reliability) of the information had to be shown. The State Court determined that the veracity prong could not be determined in this letter, or even by subsequent police work. It also stated that the details were not sufficient to establish a "basis of knowledge."

Question

Under what circumstances does the information of anonymous informants provide probable cause to issue a warrant.

Holding

The Court held that the circumstances under which a warrant could be issues on the basis of an anonymous informant could be determined by the Totality of Circumstances, in which the "basis of knowledge," "veracity," "reliability," and police follow up could all be factors.

Reasoning

The Court reasoned that a Totality of Circumstances has been traditionally used in determining probable cause for the issue of warrants. The Court reasoned that since most informants would not know the specific legal details of the Spinelli test, very few affidavits would stand the two-pronged Spinelli Test. The Court also reasoned that the Spinelli Test created artificial difficulties in establishing probable cause, that a Totality of Circumstances test would not. Justice Stevens and Justice Brennan, in a dissenting opinion, also agreed with a Totality of Circumstances test, but they found the Warrant lacking probable cause because of the material mistake in the anonymous letter.