uption" in the labor field and "bol- stering [the government's] own ability to investigate 'in order to act and protect.'" 751 F.2d at 707 (quoting Gibson I. Florida Legislative Investigation Committee, 372 U.S. 539, 544, 83 S.Ct. 889, 892, 9 LEd.2d 929 (1963)). Like the Master Printers court, we fmd that the