What is the legal test for an allegation that the indictment is insufficient to allege exceptions to criminal liability created by section 474 of the Interference with Defense Investigation Act?

18 U.S.C. 474. He contends that the indictment is insufficient because it fails to allege exceptions to criminal liability created by 18 U.S.C. 504 (1988). We disagree. "The well-established rule is that a defendant who relies upon an exception to a statute made by a proviso or distinct clause, whether in the same section of the statute or elsewhere, has the burden of establishing and showing that he comes within the exception." United States v. Guess, 629 F.2d 573, 576 (9th Cir.1980) (internal quotation omitted). The government has neither the obligation to allege an exception in the indictment nor the burden of going forward on the issue. United States v. Hester, 719 F.2d 1041, 1043 (9th Cir.1983).

II. Interference with Defense Investigation