379 U.S. 48 (1964) Cited 1,914 times 20 Legal Analyses
Holding that the government needs to show probable cause only when the taxpayer raises a substantial question that judicial enforcement constitutes an abuse of process
437 U.S. 298 (1978) Cited 522 times 2 Legal Analyses
Holding that "the summons must be issued before the Service recommends to the Department of Justice that a criminal prosecution, which reasonably would relate to the subject matter of the summons, be undertaken"
469 U.S. 310 (1985) Cited 109 times 2 Legal Analyses
Holding that the assertion that the IRS is seeking information relating to audits of other taxpayers, even if true, does not render a summons illegitimate if there is another legitimate purpose of its issuance
Stating that we review de novo the district court's rulings on the scope of the attorney-client privilege because they involve "mixed questions of law and fact" and that the burden of persuasion is on the party seeking to establish that the privilege applies
26 U.S.C. § 7602 Cited 1,565 times 22 Legal Analyses
Granting power to issue summons to investigate, inter alia, the "liability of any person for any internal revenue tax or the liability at law or in equity of any transferee or fiduciary of any person in respect to any internal revenue tax"
Fed. R. Evid. 406 Cited 737 times 3 Legal Analyses
Stating that evidence of an organization's routine practice can be admitted to prove that the organization acted in accordance with that routine practice on a particular occasion