Response: I do
not give legal advice, so do not construe this as advice governing any
particular situation . . . especially since I do not know the details of
whatever case you are asking about.
However, the Fifth Amendment privilege against
self-incrimination, which protects anyone from being compelled to give
testimony that incriminates them, does apply to grand jury
proceedings. The subpoena and the threat of criminal contempt
establish compulsion for the purposes of invoking the privilege, so
the witness can invoke the privilege and refuse to answer questions
posed by the grand jury and/or the prosecutor working with the grand
jury IF the answers to those questions would be incriminating. (The
Fifth Amendment does not create a right to remain silent, e.g., a
right to refuse to answer any questions; it only protects someone from
having to answer incriminating questions.) To be incriminating, the
questions must require the person to give answers which provide
evidence that could be used to convict the witness of a crime. Answers
can do this either by providing direct evidence of a crime (e.g., "I
killed John Doe") or by providing information that becomes a link in
the chain of evidence that can be used to convict someone (e.g., the
witness mentions the name of someone and they are later used to
testify against the witness in a criminal proceeding).
But, even if someone can invoke their Fifth Amendment
privilege and refuse to answer questions that might incriminate them,
the prosecutor can override the privilege by giving the witness
immunity. An immunized witness cannot claim the privilege as to any
questions that fall under the scope of the immunity.
Hope this helps.