In the US you have the 5th amendment which means you cannot be compelled to testify against yourself witnesses that may incriminate themselves would get an immu

In the US you have the 5th amendment which means you cannot be compelled to testify against yourself witnesses that may incriminate themselves would get an immunity deal before taking the stand the only time where you cannot invoke the 5th is during cross when you agreed to testify. Under certain cases in which your testimony cannot be used against you the court can compel you to testify if you refuse then you can be charged with contempt a common case for this would be a court ordering a reporter to disclose their source. But the prosecution classifying a defendant as a witness would not fly.