The Politics of Hunter Biden's Immunity Deal

The argument is that if the investigation is ongoing, that Hunter Biden won't testify in front of Congress because he'll simply invoke his Fifth Amendment right against self-incrimination. If they could ask questions specifically enough, I think those congressional Republicans are right. But for instance, this deal could never cover a state prosecution. So Hunter Biden can always say, well, you can't ask me what my drug use because a state could prosecute me for that so I'm invoking my Fifth Amendment right.