Defying subpoenas

Lawful subpoenas — issued by congressional committees, courts, or grand juries — compel testimony and document production from those who can provide them. Refusing to comply is a direct breach of the oversight relationship the Constitution and statute set up. Concrete forms include outright refusal by witnesses, blanket assertions of privilege that go beyond what privilege actually covers, refusals by agencies to produce documents the law makes available to Congress, and "compliance" that withholds the substantive material requested. Litigation over the scope of a subpoena is ordinary; defiance is what happens after the scope is resolved and the subject refuses anyway.