An Internal Revenue agent visited taxpayers and interviewed them in connection with an investigation of possible civil or criminal liability under the federal income tax laws. The taxpayers then obtained from their respective accountants certain documents relating to the preparation of their tax returns. The taxpayers transferred the documents to their lawyers - respondent Kasmir and Fisher (D). Upon learning of the whereabouts of the documents, the Internal Revenue Service served summonses on Ds directing them to produce documents listed therein. The attorneys raised in defense of the enforcement action the taxpayer's accountant-client privilege, the attorney-client privilege, and Fourth and Fifth Amendment rights. In each case, the summons was ordered enforced by the District Court, and its order was stayed pending appeal. On appeal, Ds raised only their Fifth Amendment claim, but they argued in connection with that claim that enforcement of the summons would involve a violation of the taxpayers' reasonable expectation of privacy and particularly so in light of the confidential relationship of attorney to client. The Third Circuit Court of Appeals affirmed the enforcement order, holding that the taxpayers had never acquired a possessory interest in the documents and that the papers were not immune in the hands of the attorney. A divided panel of the Court of Appeals for the Fifth Circuit reversed the enforcement order; the documents would have been privileged from production pursuant to summons directed to the taxpayer had he retained possession. It reasoned that the taxpayer retained, after the transfer to his attorney, 'a legitimate expectation of privacy with regard to the materials he placed in his attorney's custody, that he retained constructive possession of the evidence, and thus . . . retained Fifth Amendment protection.' The Supreme Court granted certiorari to resolve the conflict created.