These cases involve the validity of two civil investigative summonses issued by the Internal Revenue Service (IRS). The IRS began a formal tax investigation of Howard. Howard was arrested on a drug charge. Contraband and documents had been seized in a search of Howard's residence under a search warrant. The IRS got copies of all the documents. The IRS then issued summonses to the taxpayer's attorneys and accountants. D, an attorney, and a certified public accountant, had prepared Howard's tax returns for several of the years in question. The summons required Ds to produce and testify as to two categories of documents. D was to bring all records in his possession of financial transactions by Howard or corporations in which Howard had participated for the years 1974 through 1978. D was to produce the workpapers he had generated in the course of preparing Howard's tax returns for those years. D refused to comply with any part of the summons, citing the attorney-client privilege. P filed a petition to enforce the summons. Ds made blanket assertions concerning the attorney-client privilege, the work product doctrine, and their client's fifth amendment privilege, all of which the district court rejected. The district court issued an order granting P's petition in full. D and his law partner, Orr, who had also been served a summons appealed.