Los Angeles police officers searched an apartment pursuant to a warrant. Based on the search, the officers arrested the occupants (plaintiffs) for conducting a bookmaking operation. After seizing the occupants’ bookmaking records, the officers turned the information over to the Internal Revenue Service (IRS). Relying on these records, the IRS assessed the occupants’ back taxes. A judge ruled that the police search of the apartment was illegal due to defects in the warrant. The occupants took the position that the United States’ (defendant) IRS claim should be dismissed because the evidence upon which it was based had been obtained illegally. The case came before the United States Supreme Court.