Police received an anonymous letter implicating Sue and Lance Gates (defendants) in an elaborate illegal drug scheme. The letter contained many details about the couple and their drug business, including how the Gateses would obtain their illegal marijuana to sell and when the next transaction would occur. Based on this information, the police department conducted its own investigation which revealed that parts of the informant’s tip were true, and only one discrepancy between what the informant said would happen and what did happen was uncovered. The police were able to secure a search warrant of the Gateses’ home and car where they found drugs, weapons and other contraband. The Illinois Supreme Court upheld the lower court’s ruling that the search was unlawful. The court held that the anonymous letter and the police detective’s affidavit outlining the police investigation did not support the necessary probable cause needed to obtain the search warrant.