Source: https://www.justice.gov/jm/criminal-resource-manual-1745-elements-perjury-federal-proceeding-under-oath
Timestamp: 2019-04-21 01:32:10+00:00

Document:
The first element of a perjury offense is that the defendant must be under oath during his testimony, declaration or certification, unless the perjurious statement is an unsworn declaration permitted by 28 U.S.C. § 1746. No specific form of oath is required. The oath must only be sufficiently clear that the declarant is aware that he or she is under oath and required to speak the truth. Proof of the competency and authority of the oath-giver may be required for prosecutions under section 1621. See, United States v. Debrow, 346 U.S. 374, 377 (1953) (indictments reinstated although government failed to allege name of oath administrator).
PRACTICE TIP: This element may be proven by the testimony of a person witnessing the defendant's false testimony or, for perjury before the grand jury, by the transcript of the defendant's grand jury testimony. United States v. Abroms, 947 F.2d 1241, 1247 (5th Cir. 1991), cert. denied, 505 U.S. 1204 (1992). The jury may review the transcript during their deliberations. United States v. Saget, 991 F.2d 702, 711 (11th Cir.), cert. denied, 510 U.S. 950 (1993).
PRACTICE TIP: Although case law once considered the oath-giver's authority a question of law, the United States Supreme Court held in United States v. Gaudin, 115 S.Ct. 2310 (1995)(18 U.S.C. § 1001 prosecution) that the jury must decide all elements of the offense. Therefore, each element of the offense should now be explicitly referenced in jury instructions. Thus, for section 1621 charges, a jury instruction should address the defendant being under a validly administered oath in a Federal proceeding while making the declaration at issue. Section 1623 does not require proof of the identity, authority and competence of the oath administrator, only that the defendant testified under oath.

References: § 1746
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 § 1001