"Congressional action is analogous to what you see in a criminal context," Bussert said. "What you often see is the U.S. attorney's office or law enforcement agencies working with the U.S. attorney's office coming in and gathering documents from a company or an individual. They may have valid Fifth Amendment claims - they couldn't be compelled to speak to agents or what have you - but they can't refuse to comply with the subpoena for documents. You have to produce those - even though those may be incriminating."