Osborne Sheppard (defendant) was a suspect in the murder of Sandra Boulware. Detective Peter O’Malley drafted an affidavit to support an arrest warrant for Sheppard and a search warrant for Sheppard’s home. The district attorney agreed that the affidavit set forth probable cause supporting the warrants. O’Malley could not locate a warrant application form, because it was Sunday and the court was closed. O’Malley found a previously used warrant application form. The form was for a different suspect in a different district and authorized a search for controlled substances, which was a more limited scope than called for in O’Malley’s affidavit. O’Malley used a typewriter to make various changes to the form and then presented the form and affidavit to a judge. The judge told O’Malley that he would make the changes necessary to validate the warrant and then sign the warrant. The judge then made certain changes to the form in O’Malley’s presence and signed the form. A reference to “controlled substances” was not removed from the portion of the form that would constitute the actual warrant when signed. O’Malley searched Sheppard’s residence pursuant to the signed warrant and found incriminating evidence. Sheppard was convicted. The Supreme Judicial Court of Massachusetts reversed the conviction, finding that the evidence obtained in the search should have been excluded because the search was broader than the warrant authorized. The United States Supreme Court granted certiorari.