Mandujano (defendant) was subpoenaed to testify before a grand jury in an investigation related to drug trafficking. Prior to interrogation by the grand jury, the federal prosecutor informed Mandujano that he had a right to the assistance of counsel and that he could be prosecuted for perjury if he gave false testimony. Mandujano gave false testimony and the United States (plaintiff) initiated prosecution on perjury charges. Mandujano moved to suppress the admission at trial of his testimony before the grand jury. The court of appeals ordered the suppression of Mandujano’s grand jury testimony on grounds that he had not received Miranda warnings prior to the grand jury interrogation. The United States petitioned the Supreme Court for review.