To answer @luigirovatti question:
- not snap-your-finger fast.
1) the witness has no choice. He or she has to deal with it.
2) if the defendant doesn’t like his attorney, he/she has to ask the judge for permission to change attorneys. That is not always approved. And that doesn’t happen in the middle of a question – it will happen during a recess in the proceedings and not while a witness (whoever it is) is on the stand.
3) a defendant can be his own attorney (no lawyer) but that usually doesn’t work well.
4) One of the reasons that judges dont’ approve those sorts of changes is that they waste the court’s time.