Funny how that does not apply to IRS officials testifying before Congress....
Our the USAG.
Huge difference. Testifying in front of Congress with it being run as a court, these people are essentially sworn in for their testimony. In court once you are sworn in as a witness and are testifying you don’t get to make an opening statement proclaiming innocence, then taking the fifth from that point on.
You are not in court nor are you a sworn in witness at a traffic stop. You can answer a few questions but if you do not like where the questioning is going you can invoke 4th and 5th amendment rights once you believe the cop is on a fishing expedition at your expense.
Testimony before a jury or other fact-finding agency is different from talking to police. Among other things, when one is giving testimony, one is supposed to give the truth, the whole truth, and nothing but the truth. Someone who gave some testimony, but then sought to plead the fifth, would have given testimony which was not the whole truth. I would posit that people should still have the right to plead the fifth, but it would be legitimate for jurors or other fact-finder to draw inferences from that in their evaluation of a person's earlier statements.
Incidentally, I think people who are employed by government retain their Fifth Amendment rights, but they have no right to continued employment if they refuse to give testimony related to what they were doing on the job.