In Kastigar v. United States, 406 U.S. 441, 92 S. Ct. 1653, 32 L. Ed. 2d 212 (1972), the United States Supreme Court held that the government can compel testimony from an unwilling witness by conferring immunity from the use of the compelled testimony and evidence derived therefrom in subsequent criminal proceedings (use and derivative use immunity). See id. at 448. The Court added that in a subsequent criminal prosecution, the government has the burden of establishing that the evidence it proposes to use is derived from a source wholly independent of the compelled testimony. See id. at 460.