Can a corporate custodian testify against the corporation in the United States?

The custodian of corporate records may be compelled to testify against the corporation in the United States regarding his or her production of those records for the purpose of authenticating them: Curcio v. United States, 354 U.S. 118 at 125 (1957). However, it appears that the obligation to testify against a corporation to authenticate its documents does not extend any further than that. The corporate officer does not "waive his constitutional privilege as to oral testimony by assuming the duties of his office": Curcio, supra, at p. 124. In the United States, a corporate representative who is also a personal defendant could not be compelled to undergo an examination for discovery except with respect to this limited question of the production and authentication of corporate records.