Do I have To Talk To A Federal Grand Jury?
There are exceptions though and those exceptions are privileges. So, there are a number privileges, the most important for grand jury purposes is the privilege against self-incrimination, your Fifth Amendment Rights. And so when you see on TV someone’s invoking the fifth what that means is their asserting their privilege against self-incrimination.
If the information that you would give to the grand jury could be used against you in the prosecution of a crime, of a charge, you have a right not to tell them. And it doesn't have to be a definitive statement. To take a crazy example, if it’s a murder it doesn't have to be, you know, yes I killed David Bowie, it can just be I was in David Bowie’s hotel room that night and that happens to be the night he was killed. It can be a piece in a mosaic that builds up enough to have a prosecutor ask a jury for a conviction.
So, there are other privileges that apply, marital privilege, spousal privilege, communications between husbands and wives have a special status in the law, attorney client privilege of course. Unless something falls within some recognized privilege if you're going to a grand jury, you have to answer the questions, you have to provide the information that they're asking for.