While 18 USC 1621 covers perjuries committed in a wide variety of Federal proceedings, 18 USC 1623 defines false declarations more broadly but is limited to those perjuries in judicially related proceedings. Federal proceedings for purposes of Section 1621 prosecutions encompass those authorized by the Constitution and Federal statutes, as well as by Federal rules and regulations. United States v. Hvass, 355 U.S. 570, 575 (1958). In Dunn v. United States, 442 U.S. 100, 108 (1979), the United States Supreme Court acknowledged that Congress passed Section 1623 "to afford greater assurance that testimony obtained in grand jury and court proceedings will aid the cause of truth," citing S. Rep. No. 91-617, p. 59 (1969). The Court, however, held that a false affidavit submitted to a Federal court in support of a motion to dismiss could not be prosecuted under Section 1623 because the affidavit lacked the formality required of court proceedings or depositions. Dunn, 442 U.S. at 108. False affidavits submitted in Federal court proceedings can still be prosecuted under Section 1621, and prosecutions for false testimony or evidence submitted during Federal civil depositions may continue to be brought under section 1621 or 1623. United States v. Kross, 14 F.3d 751, 753 (2d Cir.), cert. denied, 115 S.Ct. 99 (1994); United States v. Markiewicz, 978 F.2d 786, 802 (2d Cir. 1992), cert. denied, 506 U.S. 1086 (1993).
Section 1621 requires that the oath be taken "before a competent tribunal, officer or person," while Section 1623 requires only that the statement be made "under oath." The Supreme Court overturned a section 1621 perjury conviction in Christoffel v. United States, 338 U.S. 84 (1949), because the congressional committee that heard the false testimony did not have a quorum at the time. The Supreme Court, however, later upheld a Section 1621 conviction in which the perjury occurred before a court later determined not to have jurisdiction. United States v. Williams, 341 U.S. 58 (1951).
[cited in USAM 9-69.200]