A grant of immunity does not protect a person from a perjury charge if he or she testifies falsely. United States v. Apfelbaum, 445 U.S. 115, 126 (1980); United States v. Wong, 431 U.S. 174, 178 (1977). The immunity grant means that immunized testimony cannot be used to prove that a previous sworn statement was false. Kastigar v. United States, 406 U.S. 441 (1972). 18 U.S.C. § 6002. Thus, if two sworn statements are irreconcilable and one was made after an immunity grant, the government must prove that the one given under the immunity grant was the false one. The government may prove immunized testimony is false by using other immunized testimony from the same grant of immunity "so long as that testimony conforms to otherwise applicable rules of evidence." Apfelbaum, 445 U.S. at 131.
[cited in JM 9-69.200]