Under the common law, a juror could not impeach his own verdict. Misconduct must be established by evidence from someone other than a juror. Federal rules permit a juror to testify to any extraneous prejudicial information or outside influences that may have altered or affected the verdict. The juror may not testify to matters that occurred inside the jury room. Many states allow impeachment by a juror for activity inside or outside the deliberation room. To impeach a verdict for a juror's incorrect response on voir dire, it must be shown that the juror refused to honestly respond to a material answer that would have provided a basis for a valid challenge for cause. Questioning for misconduct may occur after the verdict is announced. Note: Hostile interrogation may be enjoined.