ILLINOIS V. GATES, 462 U.S. 213 (1983)

How should courts measure whether information based on an informer’s tip establishes ‘‘probable cause’’ to arrest or search?

Illinois police received an anonymous letter saying that Lance and Sue Gates were big-time drug dealers; that on May 3 Sue would drive down to Florida to pick up drugs and load them into the family car; and a that few days later Lance would fly down and drive the car back. When their surveillance confirmed the Gates’ unusual travel arrangements, the officers took this information to a judge, who issued a search warrant; when the officers searched the Gates’ car, they found a sizable amount of drugs.

According to prior Supreme Court decisions, probable cause could be based on an informant’s tip only if the officer offered specific evidence showing that the informant was a truthful person and that he acquired his information in a reliable way. Because the tipster in Gates was anonymous and his letter did not say how he had obtained his information, the Gates’ argument was that there had been no probable cause for the warrant.

The Supreme Court overruled its earlier cases, concluding that whether probable cause existed should be assessed by the ‘‘totality of the circumstances,’’ and that under the ‘‘totality’’ test, the warrant was valid. The Court stressed that because the tipster accurately predicted the Gates’ unusual travel arrangements, it was likely that the tipster had obtained his information in a reliable way, and because those arrangements were somewhat suspicious anyway, a judge could reasonably conclude that it was sufficiently probable that the tipster was also right in predicting there would be drugs in the car.

CLIFFORD S. FISHMAN

References and Further Reading

• Cook, Joseph C. Constitutional Rights of the Accused, 3rd ed. 1996 and 2005 supplement, sections 4:23 and 4:36.
• LaFave, Wayne R. Search and Seizure: a Treatise on the Fourth Amendment, 4th ed. St. Paul, MN: West, 2004, sections 3.2, 3.3(a), 3.3(b).

See also Probable Cause; Search (General Definition)