A corporation and two of its employees were brought to trial for conspiracy and concealing material facts in a matter within the jurisdiction of an agency of the United States. After seven days of trial, the judge directed the jury to return verdicts of acquittal to all Ds and a formal judgment of acquittal was subsequently entered. This action was based on the improper conduct of the US Attorney and a lack of credibility in the testimony of witnesses for the prosecution. The government filed a writ of mandamus for vacating the judgment. This was granted; the judge was without power to direct an acquittal in the supposed improper conduct of the prosecutor. The Supreme Court granted certiorari.